There's been a long held tradition at TFL: "Attack the post, not the poster". When we're divided on an issue, it works very well at helping the RKBA community remain cohesive.
Seems to me, the same should apply to Zumbo
As to his sincerity? The truth almost always comes out over time. It would be in our best interests to reserve judgment, sit back, and watch. Unless he screws up again, he should be given the benefit of the doubt.