Let's not confuse legality and safety ( unless your Australian, Civil Aviation Safety Authority, you work it out, I can't). The MEL is normally issued by the authority in the country of registry. The FAA one certainly does allow it. Part 27 only requires the failure of ONE pump, hence the conditions in the RFM.
My personal opinion to remedy the perceived situation would be to fit an ejector pump (jet pump for US folk) or similar arrangement driven by each of the PRIME pumps. They are identical to the transfer pumps and serve nothing more than to prime the engine driven pumps for start and then turned off. The excess fuel driving the jet pumps would only serve to transfer fuel to the supply tanks.
Flight manual then says "Failure of both fuel transfer pumps - select BOTH PRIME PUMPS TO ON".
It does go to show that we have here an "electrically powered fuel system". If one pump fails there are consequences which are described in the RFM. If BOTH pumps fail, as a failure of the pump or their electrical supply there is no information published in the RFM nor is there any requirement to. An additional in the unapproved manufacturers data might be nice but then again. "Caveat Emptor"
The axiom or principle in commerce that the buyer alone is responsible for assessing the quality of a purchase before buying.
We have a picture of evolution in which life strives for, and tends to get closer and closer to, perfection. Perhaps a better picture might sometimes be one in which life manages to get by on whatever can be botched together just well enough to work.
For a bird to bang its face repeatedly against a tree looks like pretty dodgy behaviour, perhaps as dodgy as a mammal walking on its back legs while carrying things with its front legs. A woodpecker might get away with banging his head, just as I might get away with bipedalism. But I wouldn't be at all surprised if he was just as likely to get a headache as I am to get a bad back.
Richard Riscon , Canterbury Kent