If the FBI and the NYPD don't have the footage they need within 1 week, their ability to catch the right guy will diminish, as CCTV feeds from across the country get overwritten. If the suspect can grow and keep facial hair it would probably be difficult to match against these images. They could request some from the bus centers in Atlanta, New York and every stop in between but there's only so much footage they'll be able to get their hands on, this person seems to know what they were doing and staying less identifiable in public.
That would make more sense. The distinctive backpack must have made him easily traced by cameras.
Why would he do that?
Either he was incompetent or he knows the art of misdirection. A mask that he knowing allowed to be seen would send the authorities on a wild goose chase. All of the cops would be looking for the wrong person for a long time.
A quick change, ditch all the distinctive outfit, and change into a non-descript Walmart outfit. Then take care to let no camera see his real face as he high-tails to a safe location.
There was a high-profile public murder case some years back in my area. Police stated the alleged killer wore an eye-catching band-aid smack in the middle of his face. Now for several days, I kept looking out for some dude with a band-aid until it occurred to me that the guy probably ripped it off immediately after the hit and it just might have been a red herring from the beginning. Nobody was ever caught.
"you guys are screwed; they're gonna be lookin' for army guys" ~ paraphrasing peter griffin from family guy in clown garb and make-up somewhere in Viet Nam during the war.
Edit: meaning to highlight it might be intentional to have such a noticeable thing only to discard it later (if it's not reversible or something already).