Meh. This falls under the civic religion exception, plus the Chaplain needs OPR bullets too. Invocations are as much ritual as religion, and as long as it's reasonably nondenominational it shouldn't be a big deal. The level of religiosity present in invocations, blessing and such is enough to satisfy most of the religious folks, without being too much to be intolerable to most of the atheists and agnostics. Unfortunately, loudmouthed douchebags like Weinstein can't leave well enough alone.
That said, I couldn't resist sharing this: