Friedman is a waiver caliber defenseman, Riikola isn't much better than that and POJ is extremely raw.
You're comparing apples to oranges. Any sort of internal replacement for Pettersson on that 2nd pair role will very likely yield noticeably worse results than what Pettersson would normally be providing.
These are all assumptions because we don't have the data to back any of it up. Don't get why you're being pissy about it?
Now, to the bolded. Please show recent work that affirms this, because, boy howdy, that one pretty good season is doing a lot of lifting for him here.
If the question is: has Pettersson recorded a better season before than those three, the answer is yes.
But, as you know and as you pointed out in the goaltending thread, players do have great seasons and then decline, often permanently. So, why is Pettersson guaranteed to do better there, especially since we have no
recent evidence of him being superior? I mean, if it's fair to dog on Jarry for having only one previously good season and then having a slow start to this one, what do we do with Pettersson, who's playing awful while the rest of the team is coming together? My point is simply that, while Pettersson has had moments of better play in previous seasons, we're not seeing that now. So, why are we assuming that he's better at the moment?