I doubt anyone would want to work that way while developing a project. Apparently, I can try this, but it's far from being as convenient as using Eclipse or Oracle Studio, which provide true Emacs compatibility.
Anyway, my point is Emacs keymap is really missing from C::B (unless it is implemented somehow and I don't know it.) Several IDEs provide Emacs (and Vim) compatibility for a reason.
Several other IDEs have corporate sponsorship and have full time developers to work on them. This brings some advantages (VIM/Emacs/VS support) and disadvantages as well (they try to lock your development into their IDE and dev flow to monetize it in other ways).
You have to remember that C++ developers are expensive people and their time is expensive. For example, a quality C++ developer in the US costs you about $80K + taxes + perks, for a total of over $100K per year easily. Yeah I'd love to have feature-this and feature-that added to C::B but unless I'm willing to pay them money I can't go and request that they spend their time for the features they themselves don't need.
Open source works differently. If you really need something, you (and other people who need it) bring
your own time and skills and offer to join. I'm not a C::B developer but I suppose something like this would work:
1. Check with devs if they are interested in multiple editor bindings.
2. If yes, try a quick prototype yourself to make sure it is doable and to estimate the time needed to develop production quality software.
3. Come back to C::B devs and ask about architecture to make sure you don't break any assumptions or previous design decisions.
4. Integrate their feedback, polish your code and send them your patch to enable Emacs keybindings.
Now, if you are not willing to put your own time/skills into it then you don't really need it. Why would developers want to maintain the code that you don't really need?
Disclaimer: The above is IMHO, may contain errors and unintended prejudice.