Bittuji trusts his Chief maybe more than himself, so if he sees Chief trusting his Biwi, Bittuji will trust Madhu...besides he has seen what Madhu has done and is doing for his Chief.
I am not sure abt Radha though...she seems a very weak character at the moment, easily influenced by the Bhattia's, so she might change party...but we know that RK doesn't give 2 hoots abt what she thinks or says at the moment, so no worries there.
And if RK sees or hears Radha starting to mistreat Madhu, he will get more furious with her than he already is