I didn't get that sense at all, and I have to say it seems unlikely. First, I don't think Mr. Prust being on the roster would threaten Ryan's standing on the team, it's not like we had a surplus of physical forwards on the roster or in the system. If anything, they both complement each other more than they duplicate each other, or make each other redundant.
For example, two seasons ago, Ryan and Brad Staubitz got along famously by all appearances, fed off each other and had a significant impact in how the Canadiens played against teams that use intimidation as a tactic. In my game recaps, I noted how they spelled each other from game to game, one would fight a tough guy one game, the other the next, and we'd see them applauding each other, with the guy having a 'rest' day on the bench tapping his stick to the pugilist freshly-landed in the box. I made special note of how Ryan started a fight against Steve Veilleux early in the game against the Wild, negating any need for Brad to get into it with a former teammate so soon after he changed teams.
I'm not sure if Mike Yeo is trying to instill a more offensive mindset, but this game had flow and action, and lots of physical play. We saw Ryan White engage Stéphane Veilleux in a fight right off the faceoff, which Marc Denis of RDS posited was an attempt to energize his teammates at the start of the game. I actually wondered if he had started the scrap to relieve the pressure on his teammate Brad Staubitz to challenge one of his ex-teammates during the game. Not sure if I'm misinterpreting The Code here, but if so that was a cool move Ryan.
Looking through that prism, I was inclined to think that Brandon Prust and Ryan White might develop the same relationship, that they'd compare notes on teams and who plays how, what certain players are like. I thought they'd be thankful for each other's presence.
While Ryan had a difficult season, I didn't think there was one cause, one reason for him to underperform and take up residence in Michel Therrien's doghouse for incidents of indiscipline. I attributed it to a constellation of factors such as the shortened season, change of régime and coaching philosophy, and to a tendency for Ryan to try to do too much. Ryan was also one of the players I was giving a mulligan to, since he was seriously concussed the previous season, like René Bourque, Travis Moen, and Raphaël Diaz.
There has been lots of talk of Ryan getting a "last chance", even in season last year. We need to remember that he's still young, he can still improve, and that he's shown the willingness to work hard and improve certain aspects of his game, notably his fitness. We traded up in the third round his draft year to pick him up, he was rated higher as a prospect than Ben Maxwell or Milan Lucic in the WHL.
With a clean slate, a full season, and hopefully a long, productive off-season to get healthy and train hard, I think Ryan can improve markedly on last season. He won't have Petteri Nokelainen or Jeff Halpern in the way, but will possibly have to compete for the fourth line centre position with Gabriel Dumont, maybe from game to game, at least early in the season before injuries strike. This competition will be salutary.
What I would want Ryan to realize would be that he no longer needs to go out of his way to play tough, to goon it up. While in the past there was a toughness vacuum on the Canadiens that he, the ultimate 'can do' hard-worker and team-player rushed in to fill, now with Brandon Prust, George Parros and yes, Travis Moen on the roster, he doesn't have to do it all himself, he doesn't have to tag team all the tough guys like he did when Brad Staubitz came to town. He'll be more effective and have a longer career if he focuses on hockey, works hard in practices and games to become a reliable player, but still be tough to play against. When circumstances dictate, he can stand up for himself or stick up for a teammate, but he doesn't need to run up and down the ice crashing into every opponent to prove a point or compensate for his less physically-inclined teammates. He just needs to bear down and play his game and he should be fine.