When I mentioned that I highly doubt Apple will repair under warranty, I was referring physical damage which could also have potentially caused the Wi-Fi issue.
Well you seem to be agreeing with me

I highly doubt Apple will repair your iPhone under warranty since the damage has been caused by the previous owner.
The phrasing made it look like you were saying a warranty repair would be refused as the damage was caused by the previous owner, as opposed to the current one, which was why I was asking what that had to do with anyway.
In retrospect, I think you meant that the damage was caused by any user and thus not covered.