This is all very interesting. I've just read the PDF on the RMT website.
It basically says (as part of the proposed new method of working) the driver opens the doors when satisfied its safe to do so, observes the platform train interface (PTI), receives a signal from the Train Manager to say they have completed station duties (observed the signal is clear and that the PTI was clear at the point when they stepped back onto the train), the driver then observes the PTI and closes the doors when it's safe to do so. The driver will check the signal and perform the train safety check before starting away.
From what I can work out (and please correct me if I've misunderstood), it's basically full DOO with a second member of staff standing unnecessarily on the platform and sending an unnecessary signal to a driver who is already observing the PTI and must continue to do so after the second person has re-entered the train and ceased to observe the PTI. The responsibility rests with the driver because it's still down to the driver to observe the PTI before closing the doors, and to perform the train safety check before departing.
It's basically a pointless and unnecessary door-related role being given to the RMT as a sop. The only real safety critical duties they have are to do with train protection. It's DOO by any other name and it would make far more sense to just make it full DOO and be done with it (because the responsibilities of the driver are that of full DOO, and ASLEF will expect to be paid accordingly before agreeing to taking on these duties). The TMs could then concentrate solely on tickets, assistance and safety-critical train protection. It's pointless having someone else needlessly involved in the PTI when it's all going to be the drivers fault if there's an issue anyway.
If this agreement does come in I'd expect to see, at a minimum, to see the ticket offices closed to pay for it. I also wouldn't expect the TM's completely unnecessary role in the dispatch process to be something that lasts for long.
The RMT seem to be hanging everything on the very shoogly peg that is the doors when they could probably have got their guard members a better deal if they'd just let the doors go (they pretty much have anyway!) and concentrated on the rest of the conditions. I expect most Merseyrail guards and ticket office staff with any sense have seen the writing on the wall and will be actively looking for another job. I know I would be.