http://www.theplayerstribune.com/mailbag-brendan-shanahan/
You play "the loyalty card" because a mediocre to worthless NHL player who used to be okay at the game mentoring young players is far far more useful than you're giving it credit for. In Shanny's Q&A posted above, he says that Doug Sulliman was a huge part of why his wrist shot was so good and he scored 600+ goals. Doug Sulliman was a journeyman on his best days.
I'd pretty okay with having a guy like Cleary down on the farm who is cool with showing the young kids the ropes and helping to mold their thought processes into those of professionals. He needs to never play for the Wings in the regular season again because the game has certainly passed him by. Frankly, though, I don't give one **** about a veteran's roster slot on the Griffins. You're not pissed that Louis Marc-Aubry or Jeff Hoggan is down there, are you? That's the kind of guys who are affected negatively on the roster by Dan Cleary. All of the young kids can only be affected positively by him helping to teach them what it is to be a professional.
If I thought Dan Cleary had anything invaluable to teach, I might agree with you.
If the last several years hadn't already been filled to capacity with hanging on to mediocre players, in the name of "veteran presence" and "teaching the kids" - thus far, with results consisting of nearly all skating prospects not named Larkin still being mediocre, and no tangible franchise success to show for it - I might agree with you.
I get that grizzled veterans who can't hack it anymore still have the potential to pass on their knowledge to the next generation. But for more than half a decade, Detroit has gone into the mode of, "I don't care if the vets are any good anymore; maybe they can teach somebody something". And with the duration of that approach, and how little it's panned out thus far, I just don't see the point of continuing it to the extent that they've been employing it.
Guys like Zetterberg and Kronwall can still teach others, while they (hopefully) still occasionally play meaningful hockey. If you want that from Dan Cleary, then like somebody already said, sign the guy to the coaching staff in GR.