While I agree with you, the complaint of the particular critic you're replying to isn't even about the contents of the site. It's that some of Gab's staff have, individually, said bigoted things.

Even assuming that's true (and I don't know or care if it is), it's unclear to me why it should reflect on the community. If tomorrow somebody were to leak a tape of Paul Graham or Joel Spolsky ranting about their hatred of some race, it wouldn't somehow reflect poorly on the character of anyone with a Hacker News or Stack Overflow account.

Not employees, representatives. These are things which employees of Gab have said in their official capacity representing the company (for instance, on Gab official social media accounts).

Okay. Still doesn't change anything. Stack Overflow has officially made plenty of official announcements on political issues that I oppose, despite being an active user.