Are you certain about that? Wasn’t GPL-relicensing of BSD X-server code part of the original tensions between the GPL and BSD camps? I want to say that was in relation to Gnome, but it’s been a while since I’ve looked for it.
Nintendo’s defense, of course, would be to say they received the file from a non-gzip source.
Assuming that you mean the incident that resulted in the X.org X11 distribution being actually usable for end users it was essentially the other way around. It was about XF86 relicencing originally MIT licensed code under GPL-incompatible license similar to 4-clause BSD.
you can license BSD-licensed files and changes to them as GPL, as BSD is compatible with the GPL as it contains no clause against adding additional restrictions. However, that doesn't magically remove the original license, so you can of course grab the original file and use it under the BSD license.
Nintendo’s defense, of course, would be to say they received the file from a non-gzip source.