This is my fear. If that's the situation, you can be spoofed even if you haven't logged in for a while. I'd like more information, but maybe FD don't even know themselves exactly what's going on yet.
If it's anything like the trainers for GTA and DBD, and most others going back 20 years, the name spoofing is just disinformation to cause chaos in the community.
It's just the name, not anything to do with your account/cd key/etc.
To answer whether they
need to instance with you, not necessarily, a common tactic is to spoof a "famous" streamer/youtuber/community member, but anyone they instance with is fair game, with most programs it's literally 1 click to steal someones name on a peer-to-peer network. But if you're a random unknown pubbie, you have little worry they will spoof you unless you directly instance with them,
or have them on your friends list. In most peer-to-peer games, if a hacker is on your friends list, they can mess with you without even being instanced with you.
As for what they can actually do, just killing you and forcing you to eat a rebuy is probably the most damaging thing they can do. They can disconnect you from the game, and probably have the ability to give fines, bounties, change notoriety, and effect many other variables
while they are instanced with you, but most of these things, if done to an extreme, should trigger some kind of red flag/safety from the transaction server*, so the best they can hope for is that you can't afford your rebuy.
Source: Former anti-cheat admin for TeamWarfareLeague, first hand experience with these programs learning how to identify them.
*=They could theoretically give you a hundred billion bounty, but that would most definitely trigger the anticheat protocols of any competently programmed game.