What's the rush? The guy is playing center which takes sometime to develop, especially for players that are "adapting" to the North America game and he's a high-quality prospect. Seems you want to make sure that you get the most out of that prospect. As you said, he's not even 20 yet. I know this might go against what some people might believe, but "developing" in the NHL especially early in one's career, isn't the best course for every player, and probably shouldn't happen until his overall/two-way game is at a level you don't need to worry about, or he's so dynamic on the ice, that you can't survive without him, and I feel Kulich is a guy that you can afford to take the time to bring him along slowly that doesn't need to be at the NHL level so soon.
Give him chances with call ups I'm fine with, but to give him consistent time, it feels like you are planning on stunting his growth by shoehorning his linemates to be less than desired players.