You're supposed to make games for people to have fun, not to make a political statement.
Just because you're not smart enough to believe in climate change, doesn't mean that it doesn't exist.
You aren't his boss! Don't like it? Don't play it!
No but he is entitled to his opinion, and the ability to voice it.
Opinions don't start with "You're supposed to...". Opinions start with "I prefer..." or "I might enjoy it more if...", or similar.