It's not a conspiracy - it's just ironic twist of fate...

If you make the source available as required by the licence, then that's all you're obliged to do.

If the user can't get at the source because of caching, then legally that's called "frustration", where neither side can be held liable for failure.

It's a bit like a contract says "A will deliver the goods to B via the wotsit bridge". If A fails to deliver the goods because the wotsit bridge fell down overnight, B has no comeback against A because A is willing to fulfil the contract - he just can't because the bridge is no longer there.

Cheres,
Wol