What is "established" is part of the debate too and obviously it is in some deniers interest to instead label themself sceptic. Apparently there has been a debate about this:
There was a time when denial of this issue was really skepticism, and a time for debate, but it was decades ago. At this point it’s like debating with tobacco companies who wanted to claim that smoking was good for you. It’s not a real debate, it’s dealing with people who are arguing in bad faith for selfish reasons at the cost of human lives. Why should ignorant, dangerous people (at best) and disingenuous people (at worst) be afforded any respect or time? Just because those people pretend (sometimes) to be scientific, skeptical, rational, or sincere doesn’t mean anyone else should be compelled to meet them on their own corrupt terms.
It’s like “debating” Creationists, and it’s a waste of time and it demeans the concept of debate. Don’t let cynical bastards drag you down because they learned how to just barely pretend to be skeptics or scientists.
At least that combination grants them the opportunity to be victims rather that villains