If this is about safety, to which all workers are committed, how can an agreement have been reached with Aslef? Do Aslef care less or do the RMT care more?

I think the unions are involved ina complex game of power-broking but it is clear that workers - those on the ground - are dedicated to safety.

I think it's unclear as to how and why union leadership is run, and for what reasons, but I do know that the workers are committed to the struggle for safety over profits and power.