Hey Patrick, we support from v2.0 upwards, although not as heavily tested on 2.0 and 2.1. Our tooling actually sets users up with an AVD, and our docs (http://docs.trigger.io/en/v1.2/android/getting-started.html) do say that 2.3 is not supported on the emulator.
If we do get requests from our users to change that approach, we'd obviously consider it, but at the moment, we think the significant performance and code cleanliness benefits outweigh the downside.
Although we obviously can't test every device out there, everything so far points at no device ever actually shipping with JSC after 2.2, e.g. see http://code.google.com/p/android/issues/detail?id=12987
If we do get requests from our users to change that approach, we'd obviously consider it, but at the moment, we think the significant performance and code cleanliness benefits outweigh the downside.