I don't see how that's a point that he needs to grow up, i might be 21 but i believe it'd find it as funny when i'm 30 or 35.
For all i know Pirlo might be watching Family guy and play FIFA at home, but in the game he rapes everyone.
When/if he gets more playing time and shows he is not good enough you can judge him about that.
P.S.
for the briefs moments he was used he showed he could help the team, i don't understand why Conte is not giving him playing time even when we have a comfortable lead.