You're setting up a strawman there. Cholo started both last season and this season in the NHL. He has in fact been given multiple tryouts. It was not as if he played 10 or 20 games last season before being sent down, either. He saw 52 games of NHL action. This season he was sent down earlier, in mid-December. He got less of a look because the progress the team was looking for was not there. He is not an NHL ready d-man. He's too soft and passive, and other teams are readily exploiting the holes in his game.
Look, the basic problem with Cholowski is that if he can't play competently in his own zone then he simply cannot play at the NHL level. There's no giving him a chance to put up points on the PP and sheltering him from all other aspects of the job, beyond what was already attempted. If it were that easy then Hirose would still be here and he'd be logging 7 minutes a night, almost all on the PP. Hirose, along with Cholo, have been among our best players on the PP. Being an NHL player means meeting a minimum set of standards. Until Cholo achieves that, he's going to be on the outside looking in, as is Hirose. Cholo has already gotten two good looks and a second chance. How many more chances will he receive? I get the feeling that after two years of stagnation, the team is ready to move on. Depending on how much offense Seider is able to bite off there may not even be a need for Cholowski, anyway.
I don't think I'm setting up a strawman, as much as I am openly diving into personal subjectivity, projection and conjecture.
I think it's fair if you prefer an accelerated, hyper stringent, opportunity sparse, vetting process for prospects. My only point is that by doing that, you are inevitably walking into a JD Martinez scenario down the road. I also think it's fair if you think Cholowski is a dud, and that my dichotomy is therefore irrelevant, and he's received more opportunities than you'd expect. I think man to man and zone defense troubles being the central point of the argument against more opportunity should raise suspicion though.
To your specific points, I have never advocated for the consistent use of recently drafted defensemen in the NHL. Hronek has played too much, Cholowski has played in too many different places, etc.
It's honestly baffling to me that Hronek, Cholowski, Seider and Lindstrom haven't played massive minutes together in the AHL. I think it'd be an incredibly long list of even all-time great defensemen that would look like shit if they were rushed to the NHL, played on the bottom pairing, and yo yo'd between teammates and coaching staffs in the way Cholowski has been.
Failing 'try outs' at this point in his development should be a given. My point is if they indeed have been try outs, they have not been at all comprehensive, because outside of a handful of periods where he carried Hronek a few weeks ago, and a handful of shifts with Green last year, Cholowski has
zero NHL experience playing a game in a top-4 role to this point. And he has had zero potential as a bottom pairing defensemen all along imo. His offensive attributes revolve around pacing, and if he's playing in short intervals, he's not going to be efficient enough offensively to worry about keeping around for the no 5 role.
Of course Cholowski's track record and play has proven, that if he plays in the top 4, there will be disastrous results in the short term at times. But part of player evaluation is looking past that, and forecasting what the complete product will look like with the addition of continued experiential gains. Cholowski is a much rarer prospect than he is being given credit for here. It's startling to me to see him being held up over his troubles with man to man and zone defense, in 1 third of the ice. That's the most 'experience malleable' attribute you can hope for!
So my overall counter would be similar to your argument against Cholowski, along the lines of "Look, Cholowski is a recently drafted, puck managing, passive, birds eye defensemen, and if you/he can't afford to navigate the many errors he will make while learning through each scenario a top 4 defensemen will encounter, then you are hurting his development and wasting everyones time by using him as an injury replacement, and having Daley, Nielson and Perlini literally top the list of players he's played with most frequently in the NHL."
Again, I understand seeing the fatal flaws in his game. But I won't be persuaded that zero positive reinforcement, combined with limited opportunity and a hyperfocus on the negative, is going to give you the best read on a players potential. Sometimes you just gotta bite the bullet and give the guy a chunk of games to prove he's a gamer or not and go from there.
Playing o-zone starts with a dead beat partner, no running mates on offense, and coaches orders echoing in your head doesn't really provide an avenue to prove if you are game or not. Sheltering a player all game, then double shifting him the last 10 minutes when you need a goal or 2, doesn't really give the impression that you are trying to develop his game in the defensive zone.
I don't disagree with your read on the situation as a whole. Yzerman has never mentioned his name, Blashill has never said a good word, and Lindstrom was brought up pushing us over the limit in regards to Seattle. If I was Cholowski, I would be dreaming of playing home games in Western Canada or Seattle in the near future. It remains to be seen whether that fact is a good omen, that we have great scouts and hard driving development coaches that are fine tuned and fully invested and can recognize fatal flaws when they see them, or if it's more of a matter of grandstanding and convenience, because in most orgs, Cholowski would have never played 1 NHL game at this point yet.
Hirose is a glorified PTO, and AA was one year away from UFA. Cholowski is 3 years from RFA status. Way different situations imo.