Myro and Grice on efficienty-quota preserving individual constant variant

On p. 138, Grice provides an argument why he prefers Mryo's suggestion for an efficienty-QUOTA preserving individual constant variant interpretation Z' of Z.

To accept the simpler efficiency-preserving involves a reductio or contradiction:

~a3Fad2 is corr(1) on Z.

So, by EG, Ex4~3F1x2 is corr(1) on Z.

But, on the other hand,

a is efficiently assigned in Z, so that

~3F1a2 is corr(1) on every efficiency preserving (but not efficiency quota preserving) individual constant varaint of Z -- since, as Grice notes, "F" "includes in its extension every designable object). So, Ex4~3Fxx2 is corr(o) on Z. And we don't want that. The idea of 'efficiency-quota preserving' individual constant variant avoids just that. And it's still NOT ad hoc!