I think they're both consistently wrong. I don't agree that affiliation with a university is a positive indicator if the subject is one that might be covered by a think tank.
But yes, I also think the viewpoint your comment suggests ("of course one side is always right and the other one isn't") lends a certain worthlessness to the person expressing it.
There are cases where the viewpoint "Of course one side is always right and the other isn't", has been entirely correct. For example, there was real controversy for decades over the idea that cigarettes caused cancer, that second-hand smoke caused cancer, and so on. One side was mostly good-faith research and the other side was almost entirely paid shills trying to muddy the water.
Climate change seems to be mostly the same situation.
The Soviet propaganda machine is another example - it presented an intellectually sophisticated "side" which was dictated by politics, not any genuine interest in reality.
I think we have to be careful, because propagandists know that most people want to be even-handed, and they take advantage of this to make fringe views seem credible. This makes "there are two sides, the truth must be somewhere in the middle" an entirely unreliable intellectual shortcut.
So if you want to argue that US right-wing think tanks are no worse, in terms of bias and distortion, than academia, I think you need to make that case in more detailed terms, and not just dismiss the very idea that one side could be more systematically biased than another.
"Do cigarettes cause cancer?" is both a single issue, and one with no middle ground you could occupy if you wanted to.
"Left vs Right" is not a single issue; claiming "Left is always correct" immediately commits you to one end of a very large number of dimensions.
And what bothers me about the idea "university-affiliated people are more credible; think-tank affiliated people are less credible" is that if you follow it, you will conclude that the left is correct, and the right is wrong... and it's not necessary to look at what the issue is, or what positions each side has taken, before coming to that conclusion.
But yes, I also think the viewpoint your comment suggests ("of course one side is always right and the other one isn't") lends a certain worthlessness to the person expressing it.