There are two things that would ameliorate the effects of bogus claims:

• The simplest implementation of ownership transference wouldn't carry across any XP appropriate to the node's rep - no immediate XP advantage
• A time limit (say, half an hour) from time of posting could be imposed after which a petition for ownership change is much less likely to be granted.

These don't eliminate the possibility for abuse, but do reduce the attractiveness and likelyhood while allowing the vast majority of valid claims to be processed.