Rambling notes are very common with people who have psychological problems. This does not sound terrorist related. It sounds more like a very sick young man with many problems. A loner - not many friends - anger festering - didn’t speak much. All it takes is one rejection from a girl to set him off.
That may well be the case here, but we have no idea because they have said so little about the contents of the note.
In fact, what little they have said about the contents (the perp inveighing against the debauchery and the wealth of the students there and signing it “Ismail X” or some such) seems to rather cut the other way.
By the way, being a sick young man with problems and perpretrating an act for ideological reasons are not exclusive things.
Either-Or thinking. He was both. Most terrorists are very sick young men.