It seems like what really got him suspended was the racist undertones in the letter he wrote. Such gems as "I myself am tired of having to pay my own extremely overpriced tuition to make up for minorities not paying theirs." and "In fact, 3 out of 3 students just in my class that are "minorities" are planning on returning to Africa and all 3 are getting a free education ON MY DOLLAR. I bet the staff here is wondering how a swastika ended up in a bathroom."
My gut tells me that combined with wanting to carry a hand gun led to just to the concern of the administration.