That's great for those developers but you can't expect everyone to act the same way. The fact is that you have not right for ANY support - there is even a disclaimer for that in pretty much every open source license.
I'm not talking about rights, I'm talking about manners.
Everyone has the right to communicate any way they want,
but I also have the right to call them out on that.
If you have a public, open-source project on GitHub, and you regularly accept and respond to issues/pull-requests/suggestions, you are obviously presenting yourself to the world. It is basic courtesy to not be hostile in such communication.