Yes, Comcast should definitely fire the rude customer service agent. Dealing with frustrating, condescending people in customer service departments is unfortunately a frequent occurrence, but it should never be knowingly tolerated. If a company has definitive proof that its employee is not being respectful and fulfilling his duties, he should no longer be employed with the company.
It Comcast expects to seen a clear and present message to its CSR staff that customer harassment is not tolerated under any conditions they need to terminate the CSR who was on that viral call. His conduct exceed boundaries customer retention efforts and reached the level of customer harassment. It they expect to get FCC and FTC approval for their merger with Time Warner this need to be addressed in a very public manner.
Yes, Comcast should absolutely fire the customer service rep from the recent viral call. He represents everything that people dislike about Comcast, and Internet Service Providers in general. That aside, the CSR behaved in a manner that would generally be considered boorish, which is the exact opposite of how someone in his place should act.
I think they should fire the employee or change their policies if this is the kind of behavior they encourage. I have found myself in similar conversations with cable company reps and it is truly awful, but because they have close to a monopoly I don't believe this business practice will ever change.