Sadly, the author of TextSecure doesn't think so. He thinks side-loading of apps and alternate app stores are a problem (he says that allowing installs that don't come from Play store is "returning to desktop security model which is completely broken" [1]). He also opposes TextSecure being on f-droid, etc.

[1]: https://github.com/WhisperSystems/TextSecure/issues/127

Please see http://support.whispersystems.org/customer/portal/articles/1...

If you can suggest viable alternatives, I am certain that the team would love to drop Google from it.

I'm also running CyanogenMod without the mothership, and that's exactly what I thought. While apps such as TextSecure appear to have a good reputation needing to install probably backdoored proprietary software to obtain them seems to defeat the objective.

seems that they are trying to replace Google's push API with a websocket-based solution. See https://github.com/WhisperSystems/TextSecure/issues/1106