I'm not sure they can actually respect that 30 days absolute commitment. Let's say some internal tool flags a suspect conversation, it bubbles up and a human operator reads it and it looks like evidence of a crime. Then, that employee is legally bound in many jurisdictions to prevent the destruction of that piece of evidence.
It's one thing to commit to a "everything is deleted when you press delete" automatic policy. It's quite another to say "we'll keep some stuff for up to 30 days, look inside it for any malfeasance, then pinky promise we'll delete it".
It generally goes without saying that legal obligations must be met. Before this 30 day policy they already had to comply with subpoenas and government retention requests.
Same with CSAM policies for any cloud provider. Doesn’t matter what the retention policy says, if the law says otherwise, the law wins. And there is no obligation to spell out every law in every country that might change how data is handled.
They write "We will require 30-day retention for all traffic on Mythos-class model". For potentially criminal content, maybe it's not "we", but "the authorities" that require the retention?
... and now I wonder if "we require retention" leaves the door open to retention that is not required, but let's say convenient.