I work in DX/Evangelism at MSFT and a lot of work around containers, etc, at the moment is easier on *nix than it is on Windows (for me). I've got both machines as well as a Windows VM on the Mac if I need something there...
Which would be Chrome then (since it dominates browser share), instead of Safari.
Perhaps the person making the screenshots wanted to use a *nix system, but didn't want to be caught showing off the competition's product.
Personally I use Safari when I'm on battery all day (coffee shops, etc.), Chrome when I need multiple profile support, and I tend to split Chrome/Edge when in my Windows VM.
I do sorely miss using a Mac (first time after nearly 10 years that I don't have one at hand, and it's a drag on productivity for me when I need to talk to Linux servers or run some tools locally), but I don't think anyone would blink twice if I brought my own Mac to the office, even considering that I'm at an European subsidiary.
I think I remember about ten years ago somebody got fired from Microsoft for posting a photo of a MacPro (or two) being unloaded on the Microsoft campus. (Even though Microsoft was, of course, developing Office for Mac back then, so it was kind of obvious there had to be a couple of Macs around...)
My memory might be playing tricks on me here, but if it's not, things must have changed quite a bit.