Its not about the ETs (Personally I dont take them against capable competition preferring 6 ERs). Its about depleting the F14 of its 2 54s. Once thats done you have at least twice the payload of faster, longer ranged MRMS.
Of course the F14 could take up to 6 Phoenix, but that has its own drawbacks. Really it depends on how the missile is modelled, and I cant answer that.