Bjørn Lomborg was a hipster economist who denied man-made climate change and had an embarrassing amount of clout in Denmark:
But it’s true that those who opposed him tried to paint his criticism as a if it had been denial because that’s a strawman that is easier to argue against.
If someone comes out saying “climate change is man made and unless we do something the Oriana going to boil away in 2 years, our only option is to start throwing ice cubes into the ocean!” Then it’s perfectly resonable to argue that the prediction is wrong, and that even if it was accurate the proposed solution isn’t cost effective and that better solutions exist, that doesn’t mean you are arguing against the main premis of manmade climate change.
Now the meat of the debate around Lomborg is really if his predictions stack up against the predictions he criticized.
I say this because one of the biggest problems of every single group or organization that I've seen built around progressive/left/liberal ideas is the tendency to believe in the "everyone has a right to be heard/speak" which leads to everything being dominated by the loudest individuals who are almost always full of BS.
Honestly, I've identified this tendency as the #1 reason why such groups do so poorly in politics, except in situations where the values are just a PR front for a more traditional power structure.
But I think it is making it more confusing that you conflate left, liberal, and progressive. They have some overlap and shared meanings but are also different things.
The "everyone has a right to be heard" thing you mention is specifically a liberal value. Others may or may not subscribe to it to varying degrees but in my view it is core only to that one.
Scandanavia is pretty firmly liberal from what I can see. I mean just the other day here there was a good conversation about how the entire wealth of norway is based on nonrenewable resource extraction. Not really anything leftist about that.