Someone on the Discord server mentioned that the original Assault Model by Nanogrrr was different than the other ones ripped from the multiplayer version of Krystal. This model appeared to have been the one used in cutscenes, and it was known that the legs had odd missing features back before Nanogrrr corrected them. That lead to the question of whether or not the characters have any legs during the Star Fox Assault Briefing scenes.
While the whole theory that the Star Fox team voluntarily amputated their legs to help with handling high g environments has been conclusively busted (language warning), I did a little research and found that most characters during the briefing cutscenes do not have legs. Some don't even have their pelvis! It's obviously to save time animating and perhaps improve performance during those scenes, since the developers knew those parts of the characters wouldn't be seen anyway. At least, not without emulator tools. Check out the video to see what you can do with the Free Look mode in the Dolphin emulator. I also included more images of characters below that were not in the video.