It means that something like the excellent annotated source reviews by Fabien Sanglard of Quake[1], Quake2[2], Q3[3], etc.. aren't possible.

Nor any ports to attempt ot make it compileable/runnable.

Code isn't supposed to be hung on a wall. If you can't even collaborate to make it work again, it does lose a lot, and waiting ~95 years isn't really a practical alternative.

Will the website stay up that long? Is archive.org allowed to preserve it?

[1] http://fabiensanglard.net/quakeSource/index.php

[2] http://fabiensanglard.net/quake2/index.php

[3] http://fabiensanglard.net/quake3/index.php