Typically, people who are trying to defend themselves from nation state threat actors aren’t using iPhones or stock Android phones, and absolutely wouldn’t use safe browsing if they did.
I don't think it's about the FBI as much as the rest of the three-letter soup. NSA, CIA et al. most certainly are a threat to anyone outside the USA holding valuable secrets.
It always should have been. I'm not sure anyone would not class them as a nation state threat level. It's one of the most powerful government agencies in the most powerful nation in the world. If they don't fit that definition who would?
Ever heard of Edward Snowden? He exposed how three letter agencies were engaging in mass surveillance, even including American citizens in violation of their very own constitution they've sworn to protect.
Why not? Every system holding PII poses a potential threat, at the very least because every system can get hacked, and at worst because folks with “legitimate” access to that data can still abuse it.
They have a "law enforcement portal" they can log in to in order to request the data.