This sounds like a problem you will face many times in the future and therefore you may benefit from finding a solution that will solve for both this request and all similar future requests. For example, instead of writing any customised response, you could write a blog post / make a webpage that explains your approach to these types of request and then simply link to it in a reply. Then every time this comes up you…
> simply paste in “Thank you for your request. Please see [URL]”. I think this can make people feel like you don't understand them and maybe make them angry. It feels like an automatic response you would post when you haven't even read the request. I think you should at least clearly say that you don't want the requested feature in the response, then you can link to the page.
"Pull requests welcome" if you want the feature. "Fork off" if you don't.