We published a statement on our stance on neutrality of free software (and why we won't stay neutral in this case): https://f-droid.org/en/2019/07/16/statement.html
You seem to believe that Gab is wholly composed of harassers. This is simply false.
The majority of Gab users are nothing like that. AND harassers exist on every platform.
Singling out Gab like this is silly.
The reason Gab has been seized upon is because it's popular with Trump supporters, and a lot of Trump opponents are desperate to do anything they can to prevent Trump 2020.