Looking at Gab's ToS page, users aren't allowed to post: threats of violence or terrorism, 'illegal' research, personal information, anything breaking copyright, impersonation, spam (of various kinds), and anything that breaks International Law. Basically, the same kind of ToS that all other social medias abides by making the service mostly redundant.
However, Gab users CAN post 'Legal' research.
...I guess thats cool?