He has a pretty weak argument though: green also exists. And most experience it directly.
I’m not sure I follow - what do you mean?
Existence and commonality of something does not make something an important topic.
I don't mean to read minds here, but the only way I was able to parse your message is that "something" refers to suffering, and it seems you're implying that suffering exists and is common, but is not necessarily an important topic?