I basically agree, the only difference is that it's something you put into your body with potential side effects (extremely rare of course) which feels like it's crossing a different line than PPE.
Combine that with many employers never requiring other vaccines before but adding the COVID vaccine as a requirement for employment not just for new hires but people already employed and I think it was just a bit too far. Maybe if people had the option of really masking up or something instead and they refused that too would I feel better about it.
Don't get me wrong, I'm like triple or quadruple vaccinated for COVID at this point, but that's because I felt it was the best course of action. I would've not been a fan of my employer requiring it even though it's something I was going to do anyway.