Here are the guidelines for DTRPG, the most important online RPG book store:
Neither your Work, description, nor any promotional material, including blog posts or press releases, may contain racist, homophobic, discriminatory, or other repugnant views; overt political agendas or views; depictions or descriptions of criminal violence against children; rape or other acts of criminal perversion; or other obscene material without the express written permission of OneBookShelf.
Racist and homophobic views are bad, there are lots of arguments against obscene content in various private commercial contexts, but what's super wildcat here is this:
...overt political agendas or views...
According to their own guidelines, DriveThruRPG says you cannot have your work on the site if you have blog posts with your overt political views on them.
Now since all public social media communications by RPG creators is (as many have admitted) de facto promotion of their work and Facebook, Twitter et al are blogging/microblogging platforms and basically every single RPG creator has expressed at least one overt political opinion on one of said platforms and, so far as I know, none of them have asked for the "express written permission" of DTRPG, that means pretty much every single RPG book on their is banned.
Please begin reporting creators to DTRPG.