I've only experienced him polite and responsive. That said, maintaining Keras must have been an unhealthy amount of work for one person, and I think OSS developers in that situation deserve the benefit of doubt that being brusque or ignoring issues is not a character flaw, but a defense mechanism to keep their sanity.

Why do you say that?

I remember one instance of someone posting a legitimate and well-written github issue about argument unpacking in keras. Instead of addressing or responding to the issue, the Keras creator decided to publicly rant about the person on twitter, for seemingly no reason whatsoever.

Yeah, that never happened. We process dozens of bug reports and feature requests every week, and we listen to them.