My guess was he is pretty much a psychopath, kinda like Stu. Which gave him the fun idea of remaking the original killing spree, though Jill's motive must've appealed to him especially seeing as he already blogs online and is known for the "Stab-a-thons" (There totally should be a "Scream-a-thon") and the high school's film club, that and he kinda loves Jill and maybe something what Billy said in the first film. "Maybe your movie freaked mind lost its reality button, you ever think of that?"