That _might_ help in a criminal case (IMO unlikely unless you can show some requests were actually modified), but any civil case is going to be decided on balance of probabilities. A slight chance of interception probably wouldn't swing that either way.

HTTPS isn't bulletproof either, the argument could still be made with TLS

You also can't verify that the CA isn't rogue.

Or that the browser vendors that trust the CA the signed the certificate aren't just puppets for our lizard overlords.

Even if the courts allowed this to be a valid defense, it could only protect you from willful infringement. Not having knowledge of an existing patent does not stop the other party from claiming damages. If they can prove you knew that your work infringes the patent, they can sue you for treble damages from willful infringement.

They might allow it, but in civil litigation liability hangs upon the balance of probabilities rather than being beyond a reasonable doubt as in criminal trials. So a court might well allow it but that doesn't mean a jury would find it persuasive.

The law doesn't work like that. Sorry.

Don't you only need to be 51% confident? As long as fewer than 50% of all HTTP requests are modified by malicious adversaries in transit, you'd still have to pay up.