This looks like Operation Save Big Dog all over again, when Boris's people knew he was doomed but were just trying to help him survive each day.
I think the theory is that the PLP is extremely jittery, and Brown carries weight with Scottish MPs and Harman carries weight with women MPs, both groups that have issues with Starmer. There's zero evidence that they're popular with actual voters.
But if the response to a drubbing from voters is to say "send for Harriet and Gordon", I can't help wondering if someone in the Downing Street bunker has gone mad... or if someone is actively sabotaging their delusional leader because they know he'll never go voluntarily.