If the draft fell as you have it, I think the Saints would take Austin or Patterson. And I like Datone Jones a lot, but I do not think he would be the BPA given the other players available.
If BPA was the sole consideration, I might tend to agree with you about Austin. But BPA is never the sole consideration. BPA and at least somewhat of a team need is the usual flow. Datone Jones is ranked in my top 20 - so he fits the BPA mold. He is a rugged 3-4 DE who can start and play extensively immediately, so he fits a need too.
I think Jarvis Jones is a possibility too, but an outside one, imo. Austin would be a great weapon, but not help the defense that SP proclaims to want to focus on.
Personally, I wouldn't touch Patterson 'til the 3rd round.