I assume it means the mass of people might stop using those services (like paypal) because they don't want to support sites that talk about racist things like happens with gab. gab is different than say reddit to me because while reddit might have some people posting racist things or threatning to kill someone or rape them, but reddit will ban them or the group - but allowing for that kind of speech ends up appearing to be the main reason for a site like gab to exist.
If people can't get off their asses to stop working with a company that has worked with organizations responsible for thousands of deaths, I don't think support of Gab is going to drive anyone's payment platform decisions.
People still use the international financial system and the banking system in particular even though they have done and still do business with very dodgy people. Afaik HSBC is still alive and kicking even though it has helped some Mexican cartels launder their money, we’re talking about monsters who like to skin their victims alive.
