it should work on either gas or diesel, you shouldn't have to select. If not, that's a massive failure.
While i would tend to agree with you, when it comes to a turbine very few can run multi fuel without changing a compressor stage or two and the ones that can take a heavy efficiency penalty for it. Note this is mainly military service turbines as they have to run no mater what, and a little more cost is never an issue for them.
Personally i am wondering how they are planning on passing emissions. While yes they are are going to be way low on CO2 compared to IC engines, CNG Turbines typically have high NOX levels. I want to know what Turbine they are planning on using, i couldn't find that information anywhere.