Would it be possible to ask Dr. Z if he asked you priorly to remove a negative review (with the Spanish IP). Since if it was not Dr. Z that messaged you back then: I guess Dr. Z would merit to know too if someone is using his persona to contact mods. That is illegal and could really ruin his rep after all.
Dr. Z asked why I banned that account, with the Spanish IP, and I told him because the IP location was Spain, which didn't match the location of his practice, at which point he responded that he must have logged in while on vacation in Spain.
Since he wrote from a verifiable email address this time, I don't have any reason to question that.
Agree that asking to have certain reviews removed and not others is tacky.