My guess would be this guy.

Someone could, but that's not the Nostr address that I've been using. My identity is derekross@nostrplebs.com. if you get a new email address, you email everyone and tell them hey this is my new email address. The same goes for your Nostr address. You'd post and say hey this is my new Nostr address. If it's not from the same npub that you've been following them you'd be suspicious. This would be harder for new users that were looking for the correct Derek Ross to follow, but a little bit of work helps to alleviate pain points.