Let me throw this out there...
why is Jesus punning in Greek in the first place?
Would this have made any sense at all if this discourse between Peter and Jesus were taking place in conversational Aramaic?
In this case, the Greek pun in the New Testament would have worked the same in the
Hellenized Aramaic that Jesus almost certainly (and exclusively) spoke. Petros in Greek
is in Aramaic Kephas, which also means "rock." The New Testament Greek is probably
then a faithful translation of the original Aramaic pun in this instance. Incidentally, it may
have been Jesus who gave this disciple the name Kephas/Petos, since previously he was
known to his own family only as "Simon" (John 1:42).