I just have a feeling it was because he is from a village and he didn't want the Tyagi's to know that his family is worse off than Nimai's and if he told his amma she would've rushed over...
but now that seems out of place because RKT cleared that he doesn't care anymore and now I think its that if Rajneesh told anything else about marrying Sayali she'd find out that her son is manipulating the law to try and get into the Tyagi household and take samar's place... in which he has already 50% succeded in but now Samar brought out the amma and now Samar's in jail and the whole barsi for Rajneesh's father... wow!!! I just realised a lot is going down in the Tyagi mansion... I knew it was a lot but its way more than I thought!