Sorry, Paul I don't accept that premise, change is inevitable, its the way things are, sometimes for good sometimes for bad, but to say 'or will ever change' is not rationale.
"Events... dear boy" was the famous response from one PM when asked why things had changed. Even those who will eventually benefit from 'change' often ignore or oppose it initially, it is in the way of things.
Starmer never wanted to leave, but I agree he won't seek to rejoin, but he will seek 'a deal' or allow himself to be seen to seek 'a deal', that moves forward from where we are now, not where we were at the time of Brexit.
Now the UK is on the outside all sorts of 'deals are possible, short of rejoining, which its unlikely the EU would agree, even if the UK decided it did want to apply.
This approach could, however it turns out eventually, be Starmers 'ace in the hole' in terms of getting Labour re-elected in two years time.