If your code is meant to be an experiment, a headstart for someone else to build on, then that needs to be explicit. There's enough open source code out there. The problem is quality. All projects that are making an impact are doing so because they are actively backed and developed.

It's great that this guy works on JQuery, but I think the minimum that should be expected is to properly tie up loose ends: Fix broken links, make sure it's clearly stated that the code in question is considered done (feature complete, unmaintained, etc). Officially hand it off to someone else if possible.

You don't know what's an experiment and what's a massively successful library until you release it. JQuery was initially intended to be the experiment; presumably he had other projects he was working on at the time that were supposed to be his "real" work.

There're a bunch of counterexamples to the "all projects that are making an impact are doing so because they are actively backed and developed." Markdown is one obvious one. The Internet Explorer team was disbanded from 2002-2005, even though it was the most popular browser on the market. Several Google projects that are used by millions of people a day are completely de-staffed.

And there are many more projects that are actively backed and developed and yet are not making an impact. We'd be much better off if their developers quit what they were doing and found something else to do.