Right to reside, receiving personal care and EU residence permit

Good afternoon

My client is German and recently lost a tribunal re: his r2r; the appeal was based on his requirement of personal care from his EU citizen sister. He hasn’t got an EU residence permit or the family registration certificate so the Jacobs 2011 decision killed his appeal (or, more accurately, my argument).

My question is: If he gets the EU registration document now (he’s claiming JSA in the meantime) and them makes a new application for ESA, will he have a greater chance of getting paid?

Thanks very much for your attention, any advice gratefully received.