It could be fraud, which could be a common law non-statutory offence.
Obviously I don't think it's criminal though. Plenty of reprehensible behaviour is not criminal.
If they're
actually lying about their belief in being able to "deauthorize" the OGL 1.0(a), that seems to me to be misrepresentation. And if that lie leads to someone signing a contract, I believe that's a tort?
In a civil law jurisdiction, it might just be criminal fraud though, depending on how bad the contract is. You can't legally defraud me of my rights by willfully misrepresenting your own. It's up to 2 years in jail for doing that where I'm from.
This would usually be really hard to prove. But in the case of WotC right now, we have their own damn FAQs to go by:
Q: Can't Wizards of the Coast change the License in a way that I wouldn't like?
A: Yes, it could. However, the License already defines what will happen to content that has been previously distributed using an earlier version, in Section 9. As a result, even if Wizards made a change you disagreed with, you could continue to use an earlier, acceptable version at your option. In other words, there's no reason for Wizards to ever make a change that the community of people using the Open Gaming License would object to, because the community would just ignore the change anyway.
Open Game License: Frequently Asked Questions -- Version 2.0 -- January 26, 2004
web.archive.org