Doesn't that rule only apply in cases of intentional grounding?
That's where you usually see it, but I've seen a lineman get called for holding and it resulted in a safety. Obviously, the refs are going to give a lot of leeway in not wanting to call holding in the end zone, but this was blatant.
SD
No. It applies to any offensive penalty that occurs in the end zone (defined by the spot of enforcement rules). Intentional grounding, for some reason, is separately specifically mentioned as having the safety penalty