There were extortion calls for RK. Malik tried to Kill RK that was a straight attempt. RK pretty well understood that Malik did that to save Madhu from RK. So who blackmailed him for money. There is no need for malik to do that extortion calls where his intentions are something else.
RK might have got some clue about that so he might want to project that he hate MB so that the Blackmailer shouldn't think that MB is his biggest weakness. May be to deceive them and that Blackmailers should never try to attack MB at any cost.
RK might even got the clue that its that Bhatiya's so he might have felt that its too risky to leave his mom among these crooked people.
Lets wait and watch whats there in the store...