While I do agree GitHub is a place where people collaborate, it's also a pretty handy place to store stuff without having to host your own. If the project doesn't invite people to contribute, don't expect a polite response forever. It's like stopping your neighbor on the street corner to tell them they should paint their house white for the thermal benefits, yeah people collaborate on the street, yeah you are right, it's their house though.

I make my code open source and public so people can use it if they find it useful, not because I expect anyone to contribute.

And there’s a big fucking difference between actively hostile and “I’m not interested in accepting this change”.