The delay in the abbot announcment wasn't caused by the election, the delay was because they were waiting to an election to annouce her expulsion, so that they could then install someone, probably akehurst, who tried the same trick previously.
If they had announced her gone in December, they would had to let the CLP choose who stood in her place.
Then of course it got leaked (I would laugh my balls off if Diane was the leaker), starmer's lie was exposed and he was too scared to go through with it, hence the furious backtracking.