Is there a way to make it so that in list view in Finder a symbolically linked directory can be expanded like a regular directory? I would just switch to column view, but I'm using TextMate 2's file browser, which appears to use Finder's list view.
I have no issue with getting my hands dirty with the console or editing plists if need be - I used Linux for years and fiddled with a Hackintosh for a while before switching to Mac. I'll also understand if The Mighty Apple Hath Spoken. I've just found very little on the topic. (And in my case it's on Macintosh HD so unmounting and remounting is not an option.)
One solution, as detailed here, would be to use a hardlink for the directory. It's very important that you understand the implications listed in Bob's answer as well as only use the hunlink utility (also in Bob's answer) to remove any directories created via the hlink utility.
I certainly would not recommend this solution for anyone who isn't comfortable understanding the details laid out in Bob's answer and/or for a shared system where not every user is aware of which directories are hard links and how to properly handle them.