First confirmed encounter with an INTJ

So sorry for the inactiveness recently. Life has became so hectic now that although I have many things I want to share I don't have the time. In fact it's like 2.56 am now and I really should sleep instead of writing this, but oh well...

There's this guy in my class. He doesn't behave very normally and it was pretty obvious since the first day we met him. It is known that he has some kind of condition. Some of his abnormal behaviours include:
-talking very loudly when expressing his views, in a random and interruptive way
-unable to form his speech in a continuous flow, always pause suddenly
-making hissing sounds when he's alone (not engaged in any social interaction)
-persistently talk about one topic when others have moved on to a different topic, oblivious to lack of interest in the topic discussed
-general lack of facial expression
-following people around without the awareness of how people want to stay away from him

And, not sure if coincidentally, he is an INTJ (with 99% certainty).

I have always searched for potential INTJs around me but I don't think I have found many, and I only suspected them to be because they don't really fit well into the description. But this guy, he fits almost every description of an INTJ perfectly. And really as the theory has predicted, there's nothing much to say between INTJ and INTP.

Yes, I'm sure I'm an INTP now. After this encounter, the difference between a J and a P is obvious. The degree to which a J organise his/her life and everything else is pretty scary, or maybe that's just because he has more extreme J characteristic.

Sorry I accidentally spent 20 min looking at type descriptions. Back to the topic. It's quite interesting how people can be grouped and some temperaments just seem to go well with others while some don't. And a difference in a letter could produce so much difference. Now I'm having problem dealing with him. Communication with him feels difficult. How can I convey the message that it's not so right to follow the girls to the bus stop and go home with them everyday o_o

I know he has some condition so it may not be his fault (or is it), and I do wish my class can help him instead of isolating him. However it's just so difficult to tell him what's right and what's wrong in the intuitive sense since he seems to be lacking some of the human experience. I do wish to help him in his integration into the social world, or it will cause a lot of problems, for both him and the society.