Since the offer is made by a shadowy organisation, how would we know whether it indicates anything reasonable? Companies with money to spare could use it to easily discredit competitors. First, company A offers $X (where $X might be a full-term equivalent salary or more) to a shadow broker for an exploit in company B's product. Likely outcomes include:

If an exploit is found, company A can play it for what it's worth, either accusing B of negligent behaviour, sloppy coding, defunct bug award program, etc., or exploiting the bug (via anonymously hired help) for a while, possibly in such a way that company B's customers notice the issue before company B does.

If an exploit is not found company A can still accuse company B of negligent behaviour if company B hasn't matched $X in their bug awards.

If company B has done everything right company A can pull the offer, and try to convince a reporter that this indicates an exploit was found and is being used without anyone at company B noticing. Dumber stories certainly have surfaced, and the damage could be significant.