Brahm Dutt Dwivedi who saved Mayawati from SP goons was killed on 10th February 1997. Gangster Sanjeev Maheshwari and ex-MLA of SP Vijay Singh were accused in this case.
The entire idea is about dehumanisation of political adversaries. Once adversaries have been sufficiently dehumanised, all manners of crimes against them are justifiable.
According to the post, the protestor overheard the cab driver, one Aslam, talk to someone and managed to catch 'Sanghi saale' being spoken from other end.