Im completely expecting an awkward silence and completely pretending he doesnt recognize the voice. I doubt hed bring it up on the show itself just because of he comments that will already be there. Best to pretend its just another voice and move on. I mean maybe Arin already knows exactly what character it is and will purposely avoid it. Theres no way Arin doesnt know hes in it so theres no way he didnt consciously choose to play it knowing this. So hell probably just avoid the character if its not a story requirement. (Is it?)
The Penguin Mobster in the first World isn't a requirement, but there are other NPC's that Jon voiced that are. So, it will come down to Arin either getting bored of the game before meeting a Jon-voiced NPC, or inevitably confronting it.