@garrettlynch can you please post a github issue?
Did you try with the latest 2.3.15RC binaries? Releases · NatronGitHub/Natron · GitHub
Please try the Universal (10.6+) as well as the 64bit (10.9+) binaries.
Reference to similar issue: MacPorts - Developer - Compiling against libc++ on 10.6 and using the binary on 10.7
A fix could be to ship libc++ with the 10.6 binaries.
The 10.9 binaries should work ok on 10.9+