They’re not being bothered. They are a sensible asshole. Nothing wrong with that, and they are free to express their truth of how they feel. But there’s no evidence of harassment, if they think bug reports and feature requests is abuse then they are in for a rude experience if someone is stupid enough to actually harass them.

They should just take their project proprietary anyways. The license used is a joke. Duckstation is not open source, the license is so restrictive that it is barely source available. They are not ideologically, or in practice, part of the FOSS community. So they’re free to take their toy home with them. They weren’t playing nice with others anyway.