Billy paid a fraud expert, whose whole business is apparently providing fraud opinions, but that seemed to have tipped the scales (mentioned in TFA). Very unfortunate outcome.
Well, the silver lining for Jobst in all of this is that he did build his YouTube channel (partly) on ranting about Billy, and that might be worth more than what he paid here.
https://www.ign.com/articles/billy-mitchells-donkey-kong-rec...
By all accounts it would have been a very interesting trial had it actually gone ahead.