No personal attacks were made; the posting individual was not even mentioned. Arguing against an opposing idea is permitted.
No demographic groups were mentioned. Academics are not a demographic group, save possibly in the most academic possible interpretation of the word, and are certainly not a protected demographic group.
Sarcasm only works when it has a valid point to make.
The "insipid attitude" and "authoritarian behavior" was attributed to a (non-protected) group. Now, it might be that the individual that the poster was replying to is an exemplar of that group but is the beliefs and behavior of the group as a whole that is being challenged, not the individual.
No demographic groups were mentioned. Academics are not a demographic group, save possibly in the most academic possible interpretation of the word, and are certainly not a protected demographic group.