I don't see the issue with businesses having a list of people who should not be admitted to a building no matter who guests them in. Certainly, fires were on a list of "do not enter" in a call center I worked at years ago, to avoid reprisal. My local Yelp seems to attract a different sort of troll considering the large amount of in-person interactions of its members and the psychopathic small-business owners who can't tolerate a bad review, or a series of bad reviews that reflect their attitude. This situation seems to have worked out poorly for all involved, but the policy of exclusion isn't necessarily the problem.

I don't understand why they couldn't have the desk find someone in HR or other related department (whoever issues the order) to confer with regarding this particular guest.