OK Another scenario:-
Sat in your respective towers' stops illuminated and an a/c at a holding point, behind the stops, is given a conditional line up clearance which he acknowledges and reads back correctly.
Do you then turn off the stops and perhaps activate centerline/lead in lights onto the runway at the time you receive the correct readback or wait finger poised over your lighting panel button until the landing a/c has passed the appropriate intersection.
Could taking the first action (deactivating stops after receiving correct readback) be taken as an invitation by the a/c at the holding point to proceed onto an active runway.