I couldn't watch it all but I was enamored by several things:
- Charlie has an innate desire and drive to meet and engage people in philosophy and history.
- Charlie has a very logical and litigious mind.
- Charlie was better educated than the students there at Oxford, and perhaps more importantly, better at expatiating ideas and sorting, recalling and organizing his facts in an effective way. He was almost like a prize-fighter of arguments.
- Charlie was also fair and open-minded and both willing and able (indeed happy to) change his mind on any subject if sufficiently proven wrong.
Therefore, at the core of Charlie's drive to challenge and engage others in ideas went far beyond the simple desire to prove he was and could be just as smart as any of them, but more to the point, his meeting and debating with people regularly tested his own theories and beliefs--- either they held up and were not proven wrong time and again thus crystallizing them as more assured and certain, or they WERE proven in error, thus corrected making them more crystallized, assured and certain, so that no matter what, Kirk was inevitably finding his own truth that he could be sure reflected reality and not just his own imperfect beliefs.
In effect then, at its most basic level, Charlie's logic and arguments were just too good and could not be beaten, and the Left killed him for that, as the only, final way to silence him.