I agree with what you write about trolls except Krishnan Guru-Murthy is not a troll.
Channel 4 News is a news program, it is not there for celebrities to promote their latest product. They’re warned beforehand that this is the case and some choose to ignore that and assume they can keep the interview on the topic of said product. Krishnan is renowned for turning the interview onto more controversial topics that the UK population is interested in at that time. His interview with Tarantino was focused on violence because that was an issue appearing in the news at the time.
So, where you say that Krishnan is “not interested in the topic”, you’re incorrect, he is, it just isn’t the topic the interviewee is interested in.