The code is just strange. To support Redis, it has a 2,500 line Redis adapter. It has special cases for each Redis command because it doesn't extract key position information from Redis directly.

Plus, despite the name and where it's hosted, Twitter never used it in production for Redis. Redis support was just added "because we can."

It probably works for very direct use cases, but it's one of those things that could probably bite you very severely under edge cases, and you'd be left on your own to figure out what happened.