They most certainly did draft him with the idea of developing his blocking for a season. And they said on draft day that was likely to be an issue for him but that he was one of the few guys they thought could play the y for them after some work and getting stronger. But that's all academic, anyway, because it's got zero to do with whether or not it's appropriate for the guy to talk smack in practice.
If he's making plays, he can talk all he wants. It doesn't matter how good you happen to think he is or isn't. It doesn't matter how strong or weak our defense is. And we will see whether he's talking trash if he's making plays in the regular season. I'd say if he does, that's a good thing for us, though, and not something I'm going to get on the guy for just because I can't reconcile myself to the idea that he was a second round pick when I wanted somebody at another position entirely.
On a related note, if this was Devin Street or Tyron Crawford talking smack right now, do you honestly think anybody would have a problem with it? Because I think the reaction would be overwhelmingly positive if it were coming from a guy who's not a whipping boy for no good reason.