What, then, was the point?

The "Kill the Lawsuit" bill does not appear to have actually killed the lawsuit.

The attorneys will definitely challenge this bill on several grounds. Let me name just two:

First, Act 544 does prohibit “local government entities” — except for parishes — from suing over any oil-related damages in the coastal zone. However, a local government entity has a very precise legal definition, and that definition does not fit the flood authority. So the bill actually does not prohibit the flood authority from suing. That is a very strong argument that the attorneys will make.

Obviously there's more to Barry's post there but the highlighted part is what's interesting to me.  It suggests the bill's authors may not have had the levee board lawsuit in mind specifically even if that was the ostensible reasoning behind the bill.