Do you mean (d) as I did mention that (b) doesn't seem to mention anything about being revoked. I did mention 9d.
The point of section 9d is (quoted below) is that if the license is unenforceable then there is no point in having the license. The whole point of a license is so it has some legal standing, if it is shown not to have any then it makes sense to void it, because it will have effectively been voided anyway.
"9 (d) Severability. If any part of this license is held to be unenforceable or invalid for any reason, Wizards may declare the entire license void, either as between it and the party that obtained the ruling or in its entirety. Unless Wizards elects to do so, the balance of this license will be enforced as if that part which is unenforceable or invalid did not exist."
It is a pretty common clause to have.
Severability Clause Sample Clauses: 6k Samples | Law Insider
The old OGL also had a bit about it being unenforceable.
14. Reformation: If any provision of this License is held to be unenforceable, such provision shall be reformed only to the extent necessary to make it enforceable.
If anything that's worse, that's say we can change the license you've already agreed to if we find it can't be enforced to make it enforceable. At least with the new license they can't change it on you without you getting out of it.