York isn't wrong, with Chabot, Sanderson and Chychrun ahead oh him there isn't much room for Brannstrom to play in a role he'd thrive in, that's not an indictment on Brannstrom but it will be tough for him to grow as a player here.
I'd still keep him for next year but we will likely look to move him soon,
He's wrong and his logic makes no sense based on the situation. I doubt he has seriously analyzed it. The core of his argument is that Brannstrom is an offensive defenseman who is being held back from playing offensively by a lack of opportunity (or will be). That's only true if you think he's being held back minutes-wise or opportunity-wise AND that such a situation would be remedied elsewhere. Consider:
Brannstrom is 23 and playing in the NHL, most guys are still in college or the AHL. So he isn't being held back from NHL playing time since he's playing a regular shift and isn't being healthy scratched.
Is an extra shift or two 5v5 on another team REALLY going to make all the difference? Unless you think he should be getting 19+ minutes a game, he's playing exactly what he should be playing. While his advanced metrics , giveaway/takeaways, hits, blocks, etc.. have all improved year on year, his play is not compelling a promotion either. Same goes for the powerplay. If he can't generate offense 5v5 he shouldn't be on a PP on any team regardless, so giving him more opportunity there isn't warranted.
What about another team? While another team might be less deep than Ottawa will be next season, giving him a few extra, unwarranted, minutes isn't going to make him a better player. Since he isn't displacing anyone in Ottawa with his play, he's likely getting as many minutes (or close to it) no matter what team he plays on.
What about next season on Ottawa, won't he be displaced? If we look forward, there is 4 NHL defensemen in Ottawa who will likely command more ice time than Brannstrom. That said, his role is unlikely to change since he has very little experienced competition on the bottom pairing. Kleven, JBD, and Thomson are all very inexperienced and Ottawa doesn't have the cap space for competition to be brought in to displace him. There is also the potential to play right side in the top-4 with Chychrun. That's about as good an opportunity that exists for a guy to prove he is worth extra icetime.
Maybe in a year or two there might be reason to think he's facing too much competition for top-4 ice time, but in order for that to be true, he has to be able to show it on the bottom pairing first, which he hasn't really done. All he has shown is competence, not excellence. If, next season he puts up some very respectable numbers on the bottom pairing but depth prevents moving him up, or there is some serious competition on the bottom pairing which threatens to put him in the press box (which is below the quality of his play), I could see an argument that he is being held back, but right now I think he's being appropriately used.