AFAIK, the allegation is that he agreed to sell coins at higher than market value to an undercover agent who claimed to use it for illegal purpose.
As far as you know, or as far as you think you might have kinda maybe seen someone make a thinly veiled unsupported allegation of, though you cannot remember who, what, nor where?
I have not really seen any speculation to support this person's claims, however that is what happened with previous traders who were arrested while trading on LBC.
While the fact that this case has anything to do with any deal on LBC is speculation in itself, I would really not see any other way they would have caught him breaking the law.