Just had a thought...
Even if SWR's internal disputes are resolved, GWR could still quite easily disrupt the rollout on the Reading line if either DCO or DOO is implemented. Given that all passenger services out of 4, 5 and 6 are all currently dispatched with a guard, this would be a break from the norm and I'd imagine RMT would try leveraging Reading if things, once again, turn sour between RMT and SWR. Purely speculative, but even if things are all good with SWR internally, they're not necessarily out of the woods yet.