I'd call it a difference in definition as well. This year's scenario is Montreal playing an 18 year old who isn't physically overmatched in the NHL, during a season with no pressure to win games, and with a deliberate and publicly communicated plan to ease him into the NHL + small ice without micromanaging a million defensive positioning nuances. That is a very different situation than a veteran hardass coach begrudgingly having to use a young player on a team that's trying to make the playoffs and stapling that young player to the 4th line as a punishment while screaming about defensive coverage mistakes and ripping them in the media.
The descriptive context around why and how a young player is used in the NHL (and physical readiness of course) matters a lot when considering the risk factors around a player being rushed. If he isn't clicking and earning a bigger role after the 9 games are up then I do expect them to send him down (although I don't really care if they give him 10-15 games instead, the ELC minmax stuff is unimportant IMO) but I don't have any issue with his usage thus far. He's not physically overwhelmed, he's learning at the NHL level, and there's enough positive moments for coaches to build on and instill confidence.
Eh, I think whether or not he's been NHL calibre is up for debate at the moment. I'm not arguing he's setting the world on fire but I think in his worst games he's still been a playable NHL 4th line forward, and at the very least among our top 12 forwards (personally it's hard for me to put him below 7 or 8 on our F depth chart right now). I get it, your view is that he should still be in Europe or in the AHL if they want him playing on small ice and that he should stay there until he has a big year offensively. That's a reasonable development path and I would have no issue with him being sent to the AHL tomorrow morning, but I don't think it's a binary choice between Europe/AHL or rushing a player.
The danger of rushing a player is when the coach incentivizes the player to dumb their game down to avoid getting benched by being as risk-averse as possible. That just isn't what's happening with this coach and during this season. They're scratching two established NHL veteran forwards making a combined $10.5M tonight to make room for Pezzetta and Slafkovsky, and they've kept him in the lineup despite a lot of lost puppy moments in the defensive zone so far. He's learning and improving in each game, and the young players on this team are getting the leash to make mistakes and learn in the NHL.