Publicly he said nothing nearly bad enough to be sacked.
He inferred certain things but nothing that could be construed as "gross misconduct".
Also IF they'd tried to sack him it would /could have cost a pretty penny.
Rodgers isn't stupid, he's sailed close to the wind but stayed on the right side of any possible activities n by the club.
At the same time I'm not sure why he resigned unless there's been some heavy discussions between Sundays loss and last night's announcement.