> Actually no. The same extension is OK in the Safari store by using "Cleaner - For Facebook". This is OK according to the law.
The fact that Safari allows it is not some broad-sweeping legal pronouncement. Nor is it proof that they even truly evaluated it more than superficially. It's not even validation that the extension is compliant via Apple's terms. It just means your extension got back in.
Apple could get a takedown notice tomorrow and do the exact same thing. This is clearly a risk of using the Facebook trademark, even if you're doing it in a "fair use" way.
I'm not trying to be rude here, so please don't read it this way. But bluntly, invoking Facebook's name in your extension is kicking the hornet's nest. If Facebook doesn't like it, they will send takedown notices and Apple and Google will assuredly respond to those by suspending extensions. Your beef is still ultimately with Facebook, not Google.