TBH, I also don't think he's going to be a physical guy like Lowry, but I think he's going to be asked to use his size as an asset when he makes it to the pros. Shielding the puck as you say for sure, and even just using it to separate guys from pucks (not necessarily with a huge hit), instead of just using stick checks, etc.
Definitely don't expect a full Lowry or a Jamie Benn, but I think the coaches likely don't want him to model his game like Elias Pettersson either (just as an example). I think he'll get further using the size he has as another tool in his arsenal, and it doesn't sound like he is at the moment (and likely doesn't have to in junior). I probably shouldn't have said Lowry light, but I do think him rounding out his game to use a little of his size as an asset will help him.