Basically, r/science is a private board with specific rules that aim at producing peer-reviewed scientific research. This means they should let anyone post who has something like that, regardless of the study's conclusions. This also means that any comments should be regarding the specific study or should be providing referenced citations of adding anything not included in the study.
So, should global warming bashers be banned? Yes, if all they do is spout non-referenced non-scientific non-peer-reviewed research or do not present solid logical arguments to discuss the contents of the study. This should be the case for proponents of global warming as well.
It's r/science. It's not about opinion. It's about science. That's it.
In r/science, those presenting solid scientific evidence and peer reviewed articles supporting one or another of the antithesis of your global warming religion's creed were banned. You know it, we all know it.
10 Images Show What Coastal Cities Will Look Like After Sea-Levels Rise
Let's look at some of your "solid scientific" reddit topics.
CALL TO ACTION - Please take 3 minutes today to make an important phone call.
India blames heat wave deaths on climate change
Rap News does it again... Pope Francis: The 10 Climate Commandments (RAP NEWS 33)
15 Strangest Weather Events So Far in 2015
Western Heat Wave Enters History Books; At Least Six June Records Already Broken; All-Time Records Threatened
Exxon knew of climate change in 1981, email says – but it funded deniers for 27 more years
10 Images Show What Coastal Cities Will Look Like After Sea-Levels Rise
Climate Change is making me depressed
NOAA: Hottest first half of the year in Northern Hemisphere by stunning 0.36º Farenheit
World's most famous climate scientist outlines an alarming scenario for planet's future
To be fair, your closing paragraph (bolded) proposes "equal banning." But who bans the banners?
Once you invoke the heavy hand of censorship in the guise of promoting the common good, you live with the consequences. If you don't like the consequences, don't complain here. The joke that is Reddit is being laughed at here.
Further, by your own logic your post should not be allowed. I hereby ban you from all places where words are typed on keyboards and from using electrons to move imperfect and flawed ideas.