The only real power you have is to outrank them on Google. You can't win inside their subreddit because they control the content.
Focus on making a better, more helpful resource than their Reddit thread. Create a long-form guide on your own website that directly answers the main question of their popular post. Make it more detailed, with better examples, and optimize it for the same search intent.
Then, use social media and forums to drive traffic to your guide. Don't link to it directly in their subreddit. Instead, share it on Twitter, LinkedIn, niche forums, and other relevant communities. The goal is to get enough external signals (backlinks, social shares) that Google sees your page as the more authoritative answer.
Over time, if your content is genuinely better and gets more traction from the wider web, it can outrank the Reddit thread in search results, siphoning off their organic traffic. That's the only leverage that matters when a mod is often gatekeeping.