So the vaccinated people in a pub doesn't get a health benefit from a no-unvaccinated rule, they are as likely to catch the virus from any of the vaccinated who are there as they would from unvaccinated.

I think this is probably objectively false. It is the casual lie that because vaccinated can spread the virus then there is no difference between being vaccinated and being unvaccinated. This is not an all-or-nothing situation. The likelihood of transmission from a vaccinated person is almost certainly lower, if for no other reason than that Omicron is not yet the only game in town. Would your opinion be the same if Delta was still the dominant strain?

In the specific case of Omicron the difference might not be so much, but that may be before factoring in the effect of boosters. I suspect it is still too early to draw a definitive conclusion. In any case, even if the difference is nil the fact that we may have gotten lucky with how the virus mutated in this case in no way retroactively justifies a decision to have remained unvaccinated.