Techmech, I'm not sure what you're getting at, but I believe you are quite wrong.
ZK started as Complete Annihilation, a mod that (like most Spring mods) was not only conceptually derived from Total Annihilation, but actually used the copyrighted assets from TA. But unlike the other Spring mods, CA's stated intent was to replace all unlicensed assets with freely licensed assets (open source, GPL, public domain, CC, etc) so that there would be no question - either legally or ethically - as to the propriety of distributing and playing the mod. This was one of the
primary motivations of the CA developers.
That work of switching over to completely free assets was completed by the time CA became ZK.
Since then, however, the devs have been acutely aware of licensing issues and have worked to ensure that the game's assets continue to be free. See for example Saktoth's comment on
this thread where he takes a would-be contributor to task for (among other things) attempting to include content with unclear licensing.
I don't know why you think the developers' approach to music would be any different.
The Schneidemesser pieces have explicitly been licensed by the author as CC BY-NC-ND (Creative Commons, Attribution, Noncommercial, No Derivative Works)
right here on the author's SoundClick page. ZK complies with all three requirements of the license. ZK is non-commercial, ZK has not made any derivative works, and the attribution is
right here in the ZK source distribution and even more explicitly
on the ZK website.So what's your problem?