It would depend on their reasons and their agenda. If their point is that the climate has constantly changed, that's fine. If they don't care about climate change, that's fine. If they think that climate change is part of a global Jewish conspiracy to take over the world and that incidentally 9/11 and the moon landings never happened, and JFK wasn't only not shot, he never even existed, that would be a problem because the climate change opinion is part of a pattern of them either being an idiot or a total twat.
I don't think the narrative surrounding climate change is very helpful. It's pushed on us that it's our fault but that we can improve things by changing our behaviour. This is unhelpful because it's not true, nothing we do as individuals will make a big enough difference. Nothing we could do as an entire country would make a big enough difference. Only extreme radical measures like eliminating several billion people (and the "right" people, those in countries with far worse climate changing emissions than us) would make a difference and that idea isn't acceptable. Once you start talking about genocide, climate change seems like a much smaller deal.
That's the thing. People don't want to accept that they can't make a difference. They're arrogant enough to assume that because they want to make a difference, because we need to make a difference, that it must somehow be possible to make that difference. It's not, not without taking obscene measures resulting in the destruction of huge numbers of people and entire countries.
We'd be better off long term to embrace climate change and work on developing things to help us cope with it - shields to deflect the sun's heat back into space, coastal defences to cope with rising sea levels, the idea I have to dig a massive fucking hole in the Sahara and flooding it with seawater to lower sea levels.
If only protesters would take out their anger on the people who could potentially make a difference - the scientists - humanity might actually have some hope. But tell a Just Stop Oil thug to demonstrate outside the homes of prominent scientists instead of irritating the general public and they'll look at you contemptly and go and block another person trying to get to a hospital appointment.