I really like the idea the extension is going for and it's helped a ton in blocking hundreds of your garden variety TERFs without needing to scroll their profiles for long, but I wouldn't rely on it. There's trans-friendly profiles marked red and mass-blocked because someone just has it out for them, and profiles marked green but every other post of theirs is insulting (or worse) any trans person they dislike. I'd just be careful and glance at people's accounts first before hitting the block or follow button.