Parent stated that he's sad the project is no longer maintained. That's a perfectly reasonable and human response. Parent does not have to defend having an emotion, even less provide objective truth for why he feels sad.
If you don't agree, fine. But I don't see why one would write a paragraph long statement, I validating someone's emotional response.
It's hardly a reasonable response. By casually saying that it's "sad" when a maintainer gives up on a project, GP is also including a very real and heavy implication that this is somehow wrong on their part and that they should continue to shoulder that burden, as a demand from the community. This is a really unhealthy attitude and we should all do away with it. Instead, just acknowledge that the project is now there for the taking by anyone who may be interested. There's nothing "sad!" about this whatsoever, and we should not pretend that there is.