I am not sure I understand what you’re saying.
If meta can read those messages, then they’re most definitely not e2e encrypted.
Given the historical record, you would be a fool to assume that any service run by a public company isn’t fully tapped by US intelligence agencies. They’ve been tapping anything and everything they can get their hands on, why stop at whatsapp?
Let me flip it around: what proof do you actually have that it is e2e encrypted? Zuckerberg pinky promised?
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.