So was this really Brian Moser?

Brian was 21 when he got released from the psychiatric ward in 1989 and he's been following Dexter around ever since. He’s 3 years older than Dexter who is 20 in Original Sin, so he’s had a couple of years to find Dexter at this point.

Also, Dexter throwing Tony's body to the gators and part of his hand floating up, is probably a nod to Brian's prosthetic hand. Even how Dexter kills Tony reminded me a lot of The Ice Truck Killer episode where the killer displayed his first kill in the middle of a stadium. If you ask me, it's totally plausible that this was Brian trying to reach out to Dexter for the very first time or am I reaching?