In the past there have been instances where redeployed staff have been given permanent positions at WW LHR. The closure of BFS base springs to mind.
When the GLA call centre was shut down, they were offered WW LGW with 2 free GLA-LGW return per month so they could commute.
This is unchartered water for BA. Now that WW LGW doesn't exist, anything can happen. From a moral point of view, the company does need to look after the re-deployed staff. WW LHR seems to be a logical choice as it will mean that re-deployed staff from outstations can commute and therefore reduce the disruption to their lives.
The company CAN bypass transfer lists in situations like this. It has been done before.