You're raising a red herring issue. It's not that all papers have to disclose their funding: it's that he was required to disclose any potential conflicts of interest, which in this case would have included his funding sources. In essense he committed a mild form of scientific fraud. That doesn't mean he was wrong, it does mean he was deceptive.
Which is pretty much what he's worth. He's not an astrophysicist. That doesn't mean he can't publish. Some scientists have illustrious careers without having a degree in their field. Hank Stommel comes to mind. But those guys publish important papers that draw funding from within the field. This guy's career is totally a product of having the "right" position.
That's not true of other climate change skeptical scientists, who manage to have a career without politically motivated patronage. But their work isn't so quotable, because they're tugging at the loose threads of the scientific consensus. Their research doesn't show that the scientific consensus is wrong, because they can't do that in scientific terms -- yet.
If you want to overthrow the scientific consensus it's an uphill battle. It's supposed to be. Otherwise you'd have to give advocates of perpetual motion and creationism equal status, which they haven't earned yet.