I haven't got my copy of the biography to hand, but if I recall correctly Kotkin suggests that the local Cheka members and Stalin had something of an alignment of personality/interests so that was probably an element. For example the Tsaritsyn Cheka readily went along with the subsequent round of arrests that followed Stalin's arrival.

The other aspect would simply have been half the reason Stalin was there in the first place. It is easy to ignore orders from Moscow when Moscow is far away. When Moscow sends someone down there to sort things out, it at minimum sends a message that the centre is taking things seriously.