They were mobilised more for the election campaign. Their complicity was enough as far as riots went. Vajpayee's miserable performance in 1984 elections showed Sangh didn't want to go against the anti Sikh line at the time, while Vajpayee felt strongly that the riots should be criticised. Vajpayee was very much a hindutvavadi but not without principles.
This is a spine chilling article about the 1984 riots, aftermath and the elections.
https://www.telegraphindia.com/opinion/what-about-1984-pogroms-and-political-virtue/cid/283596
"I remember a Congress advertisement that unsubtly suggested that Indians ought to vote for the party of firm governance if their taxi-drivers made them nervous, this, remember, at a time when Sikhs drove taxis in large numbers in Indian cities "
Just no words...