I had the exact same thought. However, we’re it intentional, I’d also assume more climate sites would be affected. Still, the thought that MS could be on the payroll of an oil company? Seems banal to me.
I think it's much more likely to be accidental but its easy to imagine that if someone had a beef with this particular organisation they could easily falsely report many of their mails as spam/malware. After a certain number of unrelated reports the filter is likely automated.