Subversion and GIT are tools for maintaining version control with Subversion being a centralized system and GIT designed for distributed applications. Manually building final versions of documents by storing the component parts and subordinate versions in folders is how non-tech savvy people do version control. Perhaps he is suggesting that he is not seeing a consistent versioning solution across Twitter? Or suggesting that perhaps a new version control tool will come out that is better than any of these? Who knows.
So what you’re saying is those Twitter employees really need to learn to code? Haha
Just thinking about this it does make sense. If Twitter is extremely paranoid about the possibility of outsiders reading their source code and they don’t have resources to develop version control software in-house, the old method of backing up changes by manually changing file names is a simple low cost solution.