Ehhh...that's the thing though, until he actually makes that jump and shows he can do it, i don't think he plays the sort of game that makes him a "surefire NHLer" until he demonstrates it.
Even the idea of a "PP Specialist at worst", the days of the Marc Andre Bergeron are long gone. Teams just don't keep players like that around long. If a guy can't hack it as a regular Top-4D, they very likely won't stick as a bottom-pairing PPQB. Too many reasonably offensively capable guys around these days, 1D per Powerplay Unit and really only 1 Unit that actually matters. Teams need 1 PPQB and want PKers and responsible even strength contributors on that bottom-pairing.
Look at guys like Calen Addison, given away by the Wild and just barely clinging to an NHL spot with a dumpster fire team that's the only one willing to entertain his skillset. Heck, it's where even a guy like Justin Barron for the Habs who actually has size and plays a far less risky game than Hutson, can run a PP but is still just clinging to a spot in the league.
But even if we say "worst case" for Hutson is "bottom-pairing tiny PP Specialist"...that's the sort of negligible value that keeps other teams from viewing him as anything remotely like the value he potentially has to the Habs. That's waiver fringe value. Whereas the Habs rightfully still have the whole range of potential values in front of them, right up to superstar. Never going to narrow that until he starts to establish himself in the NHL...so he just doesn't make any sense to trade. More valuable to the Habs than as a trade chip.