It seems to me that if, e.g., mandatory arbitration clauses can be binding, then so could a precondition clause allowing particular types of torts (or disallowing particular types of defenses). I imagine it wouldn't be too hard to convince a judge that engaging in a defense explicitly disallowed by the contract in dispute isn't fair play.

I guess the question is whether you can have preconditions at all on blanket licenses?

For example, if I say "anyone who sends me, by registered mail, a check for 50 EUR will be granted a license", and someone just uses my code without even attempting to send the check, is that copyright violation or contractual violation? It seems to me that would be a copyright violation, or else all copyright violations are just latent contract violations, in their most absurd extents ("I didn't sign the licensing contract they offered, but because they offered one at all, it's a contractual violation" seems to be a particularly weak defense).