I discovered this archive for early versions of UNIX, BSD, and FreeBSD. This is all court tested code, all suits for this code are settled/dismissed and there's no modern code for future lawsuits except FreeBSD (which has thus far, avoided any, as per its mission). So it is perfectly fine for UVL editors to download toy around with to research games. Note, it was all originally available for such use anyhow.
Bill Broderick from Caldera even typed up an extensive letter explicitly detailing everything that can be done with the UNIX source code that they own (16-bit UNIX 1-7 and V32); "Use, modify, distribute", source, products from source, and binaries thereof.