I haven't seen anything that says the automatic extension applies if your preparer lives in a disaster area, but you're closer to the problem than I am.  Are you filing the 1040-X to amend something on the return, or just to request abatement of the penalty?  That's not the form to file for penalty abatement.  What will work is a letter, and if the client qualifies for the "first time abatement" exception, just use that and don't go into location of preparer or client.