Don't fear. There's a very reasonable - even likely - chance that Obama will be long out of office by the time this gets to the Presidents desk.
The only thing to worry about is the last time a military execution request came before a Democrat President - JFK in '61 - it was denied. Not a good track record there.
I hope you are right.
On the other hand, these killings did take place on Texas soil. Maybe the state should prosecute?