I think this is the kind of thing professors should simply ignore. There’s meaningless, mindless chatter out there. Getting mad or hurt about it is pointless. It’s like worrying about every last thought that might be rattling about in the students’ head. Chalk it up to freedom and move on. Teach better classes. Count yourself lucky to be a professor in the first place. Take advantage of the opportunity to grow a thicker skin. It’s quite useful!