I have toured this property. You are correct in that it did sustain a lot of storm flooding and damage. As you can see in the listing photo this home is very close to the ground. In my opinion, with the current FEMA requirements this home will need to be elevated. If not, it may be uninsurable or insurable with very high rates. Being sold "as is" means that the buyer is accepting this property in the condition it is in and is not looking to the seller to provide the usual guarantees of structure soundness and system stability. What you see is what you get. You are assuming all repairs. This home will need to be purchased with cash as banks will not give a mortgage on a home that is uninhabitable.
For the right buyer, tearing this down and building a new building to FEMA regulations may be less expensive in the long run. It is listed at $165,000. The land value is $134,100. The resulting structure will give a better return on your investment too. It should be noted that homes on either side of this one are of the same design and most likely flooded as well.