Ockham's Razor is not fond of the idea of ULA shooting at SpaceX.
Agreed. Hell if we want to get all conspiracy theory, it is more likely that ULA is working in the background to make people pressure SpaceX to do more, faster, than they are comfortable with and that rush is allowing small errors to slip into the processes. Now ULA, through no direct action on its own can go to Congress and say "See, they are moving too quickly and blowing up rockets!"
Still, it is fun to think of a sniper on a building taking a shot. Totally improbable, but hell Tom Clancy build a fortune on this type of What-If.