IMO, lots of good discussion about BK losing his TA position, how nonchalant vs unusual it was, and how interpersonal or inter-academic interactions (ha - inter cubed!) may have played into it.
From the outside looking in, having had TAs and assisted professors, I would have to say, from my own experience in the trenches, BK sounds like one of those TAs that would not last long, and whom everyone would not only avoid at all costs, but may be extremely frustrated, intimidated, and/or angered by his unprofessionalism in his workplace.
And everyone would know he would be easier to get rid of during the 1st semester or quarter on board while he was still proving himself and was in somewhat of a 'probationary period', similar to a lot of jobs that have that written into the hiring agreement -- usually within 3 months, everyone regroups and checks in on how it's going and whether you're a keeper or they're going to cut you loose.
I realize the TA position was not a job job, but it was his workplace and there were monetary rewards associated with it, e.g., greatly reduced tuition/housing, if not a stipend. Those rewards/stipends are to show appreciation from the professor, department, and university for a "job well done" in assisting them in accomplishing their mission of teaching their enrolled students and upholding a level of academic excellence.
So I'm not surprised at all that they fired him in December at the end of his 1st semester. He sounds like he was a nightmare, they tried to work with him on an improvement plan, and he just couldn't or wouldn't improve on his professionalism, and so they cut him loose as quick as they could since they didn't owe him anything contractually.
Even if they didn't fire him in the 1st semester, I think, based on my experiences, he would have eventually been "voted off the island" in other ways (e.g., through seriously under-enrolled courses he was a TA for with dozens of students dropping out of an otherwise very popular professor's courses and trying to add courses being taught/TA'd by someone else), or he would have been given "bad marks" when it came to "x" number of complaints being filed against him that would be reflected in some fashion on any student reviews or performance reviews conducted.
Again, in my experience, everyone enrolled in an academic program who is investing their time, energy, and money in working towards obtaining a degree and is expecting to be able to do so in a stimulating, pleasant, supportive, and congenial collegiate environment 'as advertised' by most major universities, would avoid him and the courses he was TAing like the plague in any of the subsequent semesters he may have stayed on thereafter.
I think it must have been just awful for all the folks involved in his program, never heard of anything like it.
All JME/JMO