I live in the North and saw what was happening on the ground. The Brexit delay has angered a lot of people and even people i personally know who have voted Labour all their lives voted for the Tories today.
Most Labour MPs and voters support remain. Maybe they would have picked up a few more seats in the North if they'd backed leaving but the reason those seats have gone to the Tories is the same reason that Brexit happened, because the country has lurched to the right in favour of populism and anti-immigration.
Labour supporting that not only would have disenfranchised most of their voters but would have also come across as completely insincere and a fudge (which in fairness their final policy also was) given its clearly not what the members or the MPs in the party want. Good luck to the Labour voters who flipped to the Tories today, I hope it works out for them, but I suspect that Brexit and 5 more years, at least, of a Tory government is going to completely feck those very people over.