If you don't want to post porn, Gab allows all legal speech otherwise.
> We strive to ensure that the First Amendment remains the Website’s standard for content moderation. We will make best efforts to ensure that all content moderation decisions and enforcement of these terms of service does not punish users for exercising their God-given right to speak freely.
> As a general rule, written expression that is protected political, religious, symbolic, or commercial speech under the First Amendment of the U.S. Constitution will be allowed on the Website. User Contributions absolutely must in their entirety comply with all applicable federal, state, and local regulations in the United States.
https://gab.com/about/tos