Tone is lost in text and I don't have much background. If I was thinking of contributing to Clojure, this post is reason enough to stay away from it.
Based on your explanation, I think Hickey should have simply ignored the user's post and let that be the end of it. I mentioned "blunt" response to individual contributions. That is quite different to a blanket statement with a "we don't owe you s... - f... off if you don't like it" vibe.
Without wanting to sound flippant or rude, I think they'd be cool with that. They're talking about contributions to the core language here. Not fixing typos in a README.
In mature projects like this, all the low-hanging fruit is done. You can't just take a notion some weekend and fire off a useful pull request. It requires an investment. To make a good contribution to Clojure you have to....
- clearly define the problem that needs to be solved
- get other people on the core team to agree that it needs to be solved
- document a number of ways to solve it, discuss with the community which one will work best
- let these ideas stew for a while, people might change their minds
That's a detail that, even if specifically was mentioned, would be overshadowed by the main sentiment.