I doubt they will. Actual commits aren't going to github, just version snapshots.
I am happy they are making sources available. It would be wonderful if Apple started developing their kernel in public (I would like to read those code reviews). What tools they use should be up to the developers.
I'm not saying it's useless, but it's certainly much less useful than a proper version-history, and very much a declaration that it is in no way intended to be a collaborative project.
But I guess that shouldn't surprise anyone either. It's Apple, after all.
[1] Yes, technically "not Apple" in the sense that Node.js isn't Joyent.
[2] Admittedly partial credit at best since they've orphaned it in favor of their proprietary Metal API. I'd guess however that Metal will get open-sourced pretty soon.