That's far from factual and you are making things up. You don't need to send the actual keys to a siem service to monitor the usage of those secrets. You can use a cryptographic hash and send the hash instead. And they definitely don't need to dump env values and send them all.

Sending env vars of all your employees to one place doesn't improve anything. In fact, one can argue the company is now more vulnerable.

It feels like a decision made by a clueless school principle, instead of a security expert.