derivative right to reside through wife

wife works and looks after children in education. get cb/ctc/wtc
split from husband. he is sick. he could get esa based on her right to reside as a worker as still married.
if she finished work (assuming not done 5 years to get PR) and then she claimed benefits through her derivative RTR as a former worker and primary carer of a child in education.
could he still get ESA reliant on her derivative RTR?

Short answer, no, sorry. BUT, he could if she retains her worker status. I know, that’s another kettle of fish, with the new rules.