Personally I think it was a hobbyist rocket.
second guess would be a missile interceptor missile test, the prior publicly announced tests were either contrived successes, aborted launches, duds or failures to intercept.
Possibly some DoD types were not looking to have another “Missile Interceptor Program Fails Again” headline splashed across the media while the Republicans are politicking about cutting budgets.
I agree, there certainly weren't any reports on the longevity of that rocket and if it was some sort of "show of force" I would consider it a dud.
One only has to go to youtube and search model rockets and clubs to see how advanced these hobbyists are............
I would think a hobbyist would not play with his toys that close to LA. If something were to go wrong, it would be the very last time he played with such toys. Or breathed free air.