If he was a Demoncratic activist we can guess the answer to that question, but the thugs who killed him wouldn't have known that.
Seeing as he was a Democratic activist, I'm surprised he didn't have a gun. That gun control stuff is for us serfs, not the ruling elite.
You're almost certainly right that Sennit would not have carried a gun. The other people attacked by these scum, prior to the murder of Senitt, might well have been packing.
One of them might have made these criminals rethink their actions before they killed this man.
I will add, while sadly rolling my eyes, that if an armed citizen had shot one or two of these criminals, D.C. would have been a better place.