Quoted from rubberducks:
Regardless of what Mike has or hasn't done, why, his attitude, and what were or are his intentions, it's great that you feel like that, and aren't seeking your pound of flesh.
One way or the other this will come back to bite him and probably the buyers in the ass. If it is true - and it looks very much like it - the use of Ben's work could pose some big issues later on when something does need to get updated or a new bug is uncovered which can only be corrected by Ben. This is something to consider.