Also, if it can happen by accident then I don't really think it should be called "porting". You don't find that a linux-centric malware has "accidentally" "ported" itself to windows, likewise Intel bytecode doesn't suddenly execute on ARM chips.

The difference between "porting" and "modifying" has (at least in everything I've read in "hacker" culture) always been that porting is rarely a trivial act.