Yeah. I usually gardz it no matter what, but occasionally, I'll skip it. Flick a little water on the wall. If it soaks in at all, it needs to be primed. But, its better to be on the safe side and do it anyway. There might be crappy paint underneath the eggshell that the paste moisture can reactivate.
Or, you can skip the primer, and make whoever has to remove it have a crappy day, as well as keep your fingers crossed that the seams hold.
Also, paste will not stick to most oil base. Paint OR primer. I'd skip it altogether. If you use oil, you need to put a waterborne on top of it, so you might as well just use waterborne to begin with.