I love how BB is hiding behind the reasoning of it being a "Personal Matter" therefore refuses to intervene in any meaningful manner. As BB is a public broadcast therefore BB is the beneficiary of showcasing the relationship between the 2 parties globally, on arrival all contestants sign a contract with all terms and conditions set out such as no physical assault etc. That contract supersedes any personal issues, if a partner physically assaults another regardless of the relationship BB has the responsibility to apply the rules.
In my opinion Vishal should've walked out as I dont think Colors had any legally binding term within their contract to get him to pay the voluntary exit fine. In simple terms its not a voluntary exit, the guy was physically assaulted and the managing authorities did not take appropriate actions resulting in the defendant being forced to withdraw his participation in the show.