I stumbled across Debian's package of Wolf4SDL (the same source port I used), and it appears to be GPLv2+ with backing from John Carmack himself:
https://metadata.ftp-master.debian.org/changelogs//contrib/w/wolf4sdl/wolf4sdl_1.7+svn262+dfsg1-5_copyright I think this is sufficient evidence that Id has no issues with GPL licensing. I'll go ahead with merging the port, then. Franklin
