He could be anti-war. He could be pro-PETA. He could hate jocks. There are many reasons fanatics do fanatical things.
He could have been walking by or sitting on a cement bench that blew up.
The other day in our SMALL community at the corner of the interstate and local road was the bare breasted Peta gal and the guy holding signs. Later as I was driving home, on a STOP sign was added the words eating animals.