Why would that matter? The rules don't exempt "genuine gifts", they exempt "transfers", don't they?. Where in the rules does it say that to qualify transfers must be genuine gifts, and not be subsequently reversed, and that it is unacceptable for a spouse to agree willingly to give the other the benefit of their CGT allowance?
For IHT purposes gifts need to be genuine to become PETs (but that's not normally relevant for inter-spousal transfers anyway), but for CGT purposes, which is what we're talking about here, I'm not aware of any such restriction.