I’m not sure that this is an elegant solution in practice? Obviously, moderation bias exists (if I write a post and it gets flagged why would I want to take it down?) but if the post is a normal, rule-abiding chances are the user is just trigger happy on the flag button and there are better ways to handle that then revoking the ability for a moderator to moderate.
If this moderator is actually making spam posts then that’s also a separate issue. Moderators are meant to be upstanding members in a community and if this person is going around posting spam to your site maybe they shouldn’t be a moderator 