You didn't actually flip it around at all.

They're stating they doubt Meta would ever allow full e2ee, which is not evidence but simply speculation.

AND

They asked for a source/evidence to prove their hunch is more than speculative.

What standard of proof is required here? It’s not criminal court.

The original post I replied to simply asked for proof, without also stating they doubt meta would ever allow e2ee.

My post is more directed at other readers who might take the absence of a smoking gun as an assumption of safety.