I would answer his questions a little bit differently. Try to put emotion into it, so it sounds like you're truly confused. Being an aspie, like all of us on WP, you might have answered him in a flat voice. He, in turn, like the NT that he is, looked more at the tone of voice than at the words, and accused you of playing stupid. Tones of voice will be in <angle brackets>. Make sure to say everything in a politely (see below why).
Dining Guy: "Just what do you think you're doing?"
You: <confused> "I'm eating, same thing I do here every day; are you looking for a more specific answer?"
Dining Guy: "Oh, if you're gonna be that way to me, I suggest you leave before I call the university police and have you arrested"
You: <shocked, as in WTF> "Arrested? Are you serious? What for?"
Dining Guy: [accuses you of getting in people's way, in a very demeaning manner, while using dumb examples, and presenting them very moronically]
You: <as if trying to understand> "How did I do that? I'm sure there's a misunderstanding. Whatever I did, I didn't realize it." <apolgetic> "Sorry if there was any trouble."
With these answers, you put yourself on the right side of the "law" (the school rules, that is). By all means, report this to appropriate authorities. When this case will be investigated, records will show that you did the following.
-> Explained that you were simply minding your own business while having a meal.
-> Didn't even realize you were (supposedly) causing trouble.
-> Said you were sorry.
At the same time, the dining guy did the following.
-> Pounced on you while you were minding your own business.
-> Accused you of being a rule-breaker without considering the fact that your actions were unintentional.
-> Simply looked for a way to get someone arrested, instead of taking time to gather the facts.
It doesn't matter what you were really doing. Your goal is to present yourself as someone who made an honest mistake and apoligized for it. While it might require swallowing your pride (but only temporarily), it's most likely to result in the dining guy getting a penalty for what he did to you. Best of luck. While I never had anything like this in my college cafeteria, I completely understand your situation. On the contrary, the workers were very nice: they even said "good morning" to people and made jokes about increased coffee sales during final exam weeks. I hope other dining people are more like that than the guy you described.