Rees Moog seems to be against any form of backstop as he says the whole thing is the fault of the EU, not of Brexiteers, which seems to mean he doesn't mind a hard border down the middle of Ireland

That is my understanding, but I would put it more strongly. He opposes a hard border, but sees the entire UK responsibility being not to implement one on our side. If international law requires one - which some dispute - he is willing to delay enough to force the EU side to implement it. Then it is entirely the EU's responsibility - "we have not implemented a hard border."