Actually you are not correct, all these supposed new positions are not guaranteed, they are all subject to passing relevant tests, its not as you say. Not all Guards will remain either, so that is also wrong to assume. Every single Guard could be offered a trainee driver position doesnt mean every single one is suitable, doesnt mean every one will past the test, and could mean that ALL of them could fail which leaves them where?
The RMT will not speak to Merseyrail on the issue because Mersyrail want to reduce the total headcount, Merseyrail have given no guarantee that every current Guard will have a future with said company. Infact they have basically said the reverse that staff numbers need to reduce significantly to make it a worthwhile exercise. You mixing the Northern Rail and Merseyrail disputes does not help clear the muddy waters, they are two separate disputes.
I suppose facing the sack is not the correct terminology, a more better way of describing it would be staff being made surplus to requirements.