I've heard about such rules (e.g. hygiene rules in medical establishments).
If you're not vaccinated and you infect someone, and they die or are seriously affected by long covid, they can say that your lack of vaccination is a lack of the precaution required by the rule, and sue you for that person's expected lifetime earnings plus quintuple damages for negligence. Is that what you want?
No, but I don't expect that to be my only option. I'm suggesting a good faith effort by all to generally reduce infectious transmission. The reality now is that a vaccine gives license to spread.
If you're not vaccinated and you infect someone, and they die or are seriously affected by long covid, they can say that your lack of vaccination is a lack of the precaution required by the rule, and sue you for that person's expected lifetime earnings plus quintuple damages for negligence. Is that what you want?