Warmongers also can get a lot of tech (progress) from Debris.I am just going to point out here, that researchers require consumer goods, and I doubt you are not going to use researchers. Some people are not using entertainers in the first place, though, so I'm a little puzzled by your comment.
They also tend to have a abysmal Techcost from all those planets they capture.
So a lot weaker science already.
Entertainers have the advantage that they are highly Building Slot efficient. Using Clerks has some value, but only for high population planets (read Specialist+ focussed ones).