Not really to do with whether he should resign but I was listening to an interview with the author of a biography of Starmer (the author is very left leaning - make of that what you will), but his main point as he explained was the contradictions in Starmers stated philosophy and his actions: he claimed to be a socialist but was and apparently still is very much in favour of privatisation and market driven economics. He was a human rights advocate but his time with the RUC, the CPS and as attorney general he trampled all over human rights laws in favour of police officers and (apparently) other governmental institutions. He claims to be an avid republican yet accepts a knighthood.
The author's opinion is that he does everything simply to advance his career, and that he has absolutely no substance beyond what will be read into his actions in relation to his advancement. The author refers to him as simply a nice haircut in a good suit. which i suppose on one level is the diametric opposite of boris Johnson, but it seems that Starmer's personal advancement seems to be the main driver, so he probably wont resign.
Oliver Eagleton's the author - The Starmer Project: A Journey to the Right, if anyone interested