I think it's selfish to call a guy selfish for not being comfortable with putting something into his body. You can think he's wrong, sure (I do, as I took the jab myself). But I'm pretty strongly opposed to any of these vaccine mandates. Not everyone who refuses to get the vaccine is a selfish whack job and we continue to do a disservice by drawing these unnecessary lines in the sand.
It becomes selfish when he knows his decision is going to cost a dozen or more people their jobs. I hadn't thought about that aspect for a head coach, but assistants are very heavily tied to the coach, so I think that is a part that can fairly be held against a head coach that wouldn't apply for someone who is making the same decision without the collateral damage.
The "pro-vaccine but anti-mandate" argument held a lot more ground for me before the vaccine had full FDA approval. We mandate many vaccines. Maybe not for employment, but we do for schools which are a prerequisite for almost every type of employment. Now that the covid vaccine is on an equal ground as things like the MMR vaccine, I think the argument against it because it's not proven falls flat.
If people want to not get it and accept those consequences, that's fine. But they don't get to play the victim card. They aren't victims. This is an active free choice they are making.