Well, if you assumed that all state and local govs were as incompetent as what we saw in Louisiana, then yes, it was "clear" that something had to be done.
Thanks to Texas, it is no longer clear - the MSM was desperately hoping we'd fail in our mission to get everyone out. We didn't, and thanks to their wishful thinking and continuous coverage, we've just shown the world that incompetence isn't a defining characteristic of all state and local governments.
We accomplished the impossible in 72 hours with little to no Federal help. The onus is back on Louisiana to explain themselves. A quick glance at TXCN shows that Louisiana is dropping the ball again - they're apparently keeping aid out of some parish "to get people to leave".
The idea of weakening posse commitatus may just end up getting tossed onto the "bad idea" pile.
It is a states decision, period. If any state does not ask for the federal help, that state can go it alone as it wishes.
The one and only reason the fed could conceivably have to interfere would be in the name of saving the Union, as Lincoln did.