Sikhs & Hindus were seen as disloyal because of their participation in fight for freedom. Even Nehru sensed the impartiality of some of these British officers. This could be one reason which explains why the Army in Rawalpindi did not intervene to stop the riots.
It is not widely known that in the 30s & 40s, the British deliberately promoted socialist/Marxist ideas among younger Revolutionaries in jail as a way to weaken their roots in nationalism. Here is a first hand account from Subodh Roy who was later in the CPM.