That's a clever line of attack, but having an opinion does not constitute a conflict of interest. Otherwise there would be a whole shit-ton of recusal happening every day.
A conflict of interest usually involves some form of monetary compensation or other fiscal benefit.
It was kind of inevitable, unfortunately. After we impeach one of them for even legitimate wrongdoing, if they do not counter-impeach us, they lose perceived legitimacy, which weakens them.
They had no other strategically sound moves, when you consider their goal of hanging onto power regardless of the wishes of the voting public.