We interrupt the new Sci-Fi based format of this blog to impart a bit of SharePoint wisdom:
If you have managed metadata term sets that are part of a content type and they do not appear as a crawled property in the Search Admin, open a library where the content type is used and populate the missing field(s). Search apparently doesn't register those columns if there is no data to be registered.
I posted this because I could not find the direct answer to my question via Google. Maybe I didn't Google hard enough, but even still, here we are. Hope it helped.