Barring a catastrophic medical issue draining his bank account, exactly zero people will feel bad for this owner if he doesn't do what needs to be done here. 

The Hurricane damage will probably be classified as a Catastrophe loss, but other losses may indicate long term issues. 

This then caused a question to be raised by the lender asking the city's zoning department "If a catastrophic event occurred that required a complete rebuild of the property, would they allow for the zoning variance to continue to allow it to be rebuilt the same as it is - a duplex." 

I have to have safe options since a failure would be catastrophic .

I will likely post some information i have first hand knowledge on concerning recovering from catastrophic financial changes later in life. 

But I can tell you that is perfectly safe 99% of the time unless there is a facility malfunction resulting in a catastrophic failure (blowing up).

As far as currency collapse or nuclear war, those are catastrophic events that will not be a buying opportunity.

You should insure the property as of the closing date so any unforeseen catastrophic events are covered.

Assuming you are putting 20-25% down, you could pull a HELOC out or cash out refi in 2-3 years and use that money to replace your AC with that  I don’t know if I’d rely on interest rates going back down into the 3’s unless there’s another catastrophe.

I also have a $175,000 line of credit at the ready if something catastrophic happened.