My take on that is that he's making the shooting as memorable as possible.
He knows that the chances are he'd get caught (CCTV or whatever, or just overpowered by a good Samaritan at the scene). But will try (and as we know, succeed) to go on the run for a period. But he wants the murder hit the headlines and stay in the headlines, so there were more headline-worthy angles than the identity of the victim and which come out over time such as the bullet markings, the monopoly money etc - all stirring the pot of notoriety.
As he expects to be caught, he doesn't care if he's caught on CCTV (he has a few hours start on the team that's poring over it, who will have no idea where he's going or by what means) nor is he bothered by DNA as he expects they will identify him.
So the remaining question to me are: how long will he manage to stay on the run? Will locals, wherever he is, assist him? (ie will he get a following?). And, possibly at the crux of it - at trial, what will he say?
The trial is going to get a lot more coverage because of the headline grabbing aspects of the crime. If he is sending a message, it's going to be amplified because of that.
Even if it proves there is a completely unrelated motive, will it embolden others to take a vigilante path?