For your reasoning he should play ahl. The she season is significantly shorter than the NHL season, so get him used yo the 82 game grind so he knows what kind of conditioning he needs to embrace.Grundstrom has clear NHL potential but as he showed last year in the SHL, he looses his edge once the seasons long grind kicks in. And that is only natural for young players.
And it would be mistake to let him play in the NHL this season. He must play one or two more seasons in either the SHL or AHL To get his strength and stamina up.