King denies it in a recent interview here:
https://www.youtube.com/watch?v=WZ-DF-aMCJQ @ ~1:25:00
He basically said he left voluntarily because he didn't want to set up 5G stuff for Didio since Dan was going to kill off Catwoman anyways for 5G and instead opted to do the rest of it as Batman/Catwoman (it was one of the options Didio gave him). I mean it makes sense given how totally obsessed that Didio was with 5G and how laying the ground enveloped everything at DC.
Again I think our only source for him being fired by Harras was Rich and he has gotten stuff wrong before.
I am talking about the people in the editorial staff. His biggest supporters were people affiliated with the later Scott Snyder era in the Batoffice: people like Mark Doyle (fired), Chris Conroy who seems to be head editor of Black Label now, Jaime Rich (gone) and probably also Brittany Holzherr (who did the Supergirl book with him).