Pretty sure since MC for Windows uses Hendrik's LAV filters (which are Windows only), it gains the MVC 3D support from that in Red October. But since LAV filters require DirectShow (which is, as you probably guessed) it's limited to Windows only.
Not even sure if MC for Linux or Mac supports what's needed to get MVC 3D playback working with OpenGL and/or FFMPEG and compatible drivers - if it's supported in the Nvidia proprietary driver, you'd probably have to use old drivers which may or may not work with newer Linux distros in the future. Also pretty sure I recall reading it might rely on VDPAU too, can't recall at the moment. In my honest opinion abandoning Windows because of that was probably hasty. Not only would 3D support likely would require support in the Nvidia proprietary drivers which is no longer there like the Windows drivers, finding older drivers and using those on Linux distro and maintaining those is much more difficult than just installing older Nvidia drivers that support 3D on Windows which is much, MUCH easier to do, of course, depending on the Linux distro used.
Hendrik or Bob would likely know more (and can correct me if I'm wrong as the video side of things isn't my forte at the moment).