If you're capable of maintaining an open source project, you should be able to set up an email template. And if you're really so busy that you can't be bothered to do that, then put a message on your site telling users that the project is frozen, so you won't respond to email requests. But silence, that's something you do because you want to feel important. Completely unacceptable.
It's like any celebrity with a twitter handle, they now have to have template twitter reply or its not acceptable?
It's one thing when you have to deal with the support cases in your company when there is hard limit on how many people will be in touch with you. When you are releasing things to the world, there is no such limit. It can be one, it can be one thousand.
I too would like to have something open source one day, if I have something that I think can benefit people. I may not have time to respond to people, given my life and my health, so because of that I should not contribute? And if I did contribute in such circumstances, it is completely unacceptable?
You're literally writing this under a blog post detailing exactly that and it's also clear from the documentation of the project. What is your complaint here? That he potentially doesn't reply to every single e-mail?