I see what you’re getting at, but the point of keeping this person anonymous is to lessen their ability to be used by people as a symbol or turn them into a martyr. It’s far easier for bigots to say “remember Joe Johnson, we fight for him or whatever” and spin it their way than it is to say “remember that guy who shot the guy who hung up a flag? He’s our man!”
Not tying a name to the criminal prevents them from being immortalized because they’re not “Joe the defender” or whatever, they’re “a murderer”. There will still be bigots out there for sure, but leaving this person nameless gives them one less thing to latch on to.