I dont think that anyone is using it as an excuse to prove well.. anything.
I think it shows that he have a pretty good condition for bigger fella.
Maybe for his size and age he has at last somehow ok conditioning and stamina. But I still see his conditioning and stamina as one of his weaknesses. He obviously has problems with back to back games that are played without a resting day in between. His play looked difficult and tired in those games in regular season and playoffs in FEL. He didn't also get usually point production in those games.
But this is definitely something that can be made better with some good training. Would be definitely important to improve it for playing in the NHL.