As was pointed out when the strike first ended, we are not owed, and should not expect, complete candor from the actors. Doing press is part of the job, to promote the project, and focusing on positive aspects is expected & customary.
That doesn't mean that Con is necessarily lying through his teeth when he says, " I have nothing but love, respect, and faith in David Jenkins. Trust him. He knows what he’s doing." It could be anywhere along the range from that, to he absolutely 1000% means it with his whole chest.
(And we really shouldn't try to read the tea leaves about which is it, because even a convincing rumor of "Oh, yeah, Con totally tipped us off that he thought it was dogshit" could have professional consequences for Mr. O'Neill in real life.)
At the same time, we do not owe Con (and I'm sure he does not expect) the last word on how we feel about S2 in general and Izzy's ending in particular. Con (presumably) knows things about David Jenkins's vision for the season (and/or plans for season 3), that we do not know. That's fair, but it's also fair for us to evaluate what we actually saw.
If there's something we don't know, which (if we knew it) would make Izzy's death (and the season as a whole) work better, then--why don't we know it?
A choice was made to not show that information, and (given the way TV production works) it was probably a group decision, but the buck ultimately stops with the showrunner. He presumably didn't intend for the season finale to alienate a large (and vocal) swathe of the audience, but it abso-fucking-lutely did, so it's fair to ask what he was trying to do, and speculate about he could have done differently to have the effect on the audience that he wanted to have.
In terms of my personal reaction, I've kind of been swinging around wildly, but the basic throughline is that I suppose it might be possible for David Jenkins to dig himself and his show out of the hole he's put them in, but I'm having a lot of trouble seeing how. Especially if we add the caveat that it's a "this is what was intended and planned for all along" thing, and not an "oops, our bad" retcon.
But I'm willing to be proved wrong about that! As I've said before, maybe the little wooden boy really can pull it off. Middle installments of trilogies are notoriously hard, and sometimes they improve once part 3 is in place.
I don't think this new interview is anything game changing, but it could be a point on the optimistic side of the ledger. Maybe David Jenkins really does have a plan! Maybe he'll even be able to carry it out (even though, from all appearances, the plan for S2 seems to have had an "It's September 1st, boss"-sized hole in it)!
But ultimately, I'll believe it when I see it.