D&D night is not the same as a terrorist attack on the seat of government. Trump and co. have been blowing dog whistles for months, or just flat out calling for violence. He knew what he was getting into. "I just wanted to see what the fuss was about," is not admissible in a court of law.I don't know his intention. I'm not saying it was a shirt in good taste, but I am just saying it doesn't mean that was his intention to incite violence.
I know it's not really the same thing, but as an example I wear my "Rocks fall. Everyone dies" Tee to D&D nights all the time. It's an exaggeration. In my case for humor. In that guy's case... I dunno. For emphasis? He stayed away from the violence and that should be considered. He could just be an idiot with poor taste in clothing.