Well, they have crossed the following:
burmese x ball = burmball
woma x ball = "wall" (not to be confused with the BP morph known as the woma)
carpet x ball = carpall
blood x ball = super ball
retic x burmese = bateater
Judging from that track record, is a retic x ball cross really that farfetched? I mean, out of all of those, the woma python is arguably more distantly related to a BP than any of the others and they can hybridize.
Anyway....the whole issue of ethics aside (didn't we beat that dead horse into pulp
here?), I don't think its out of the question, and if a retic x ball is possible, a bateater x ball probably isn't either.