If someone wants to write a patch for it, I will seriously consider adding it. I believe that safely adding 2FA would be very time-consuming, so I'm not willing to do it myself or direct Slickage to do it.
2FA is going to be implemented in EpochTalk. I suppose we'll all be able to use it once the forum software has been replaced:
https://github.com/slickage/epochtalk/blob/master/app/templates/login.html
https://github.com/slickage/epochtalk/blob/master/app/templates/login.html
Old posts but relevant.
This is also from a previously-created thread: https://bitcointalksearch.org/topic/why-doesnt-bitcointalk-support-2fa-1472714
Searching for 2FA and finding these posts took me <5 minutes.