Wouldn't a defamation claim be difficult? I would think that not only would the employee have to PROVE the suspicion as false; he'd also have to prove that the employer KNEW it was false.
Then, too, what about the prospective employer who was not informed of suspicious activity, that came with the baggage, and resulted in a significant detriment to HIS business. Couldn't he make a similar issue out of it?
Anyway, instead of granting no comment re: the reason for discharge, I would state that I would not rehire--and leave it up to the prospective employer to further investigate, or not.