Based on my calculations it seems a bit overpriced.

Too many facts and each company will be different based on size of project, single family or multi family, single property or multiple properties, etc.

If it is simply the house and the tenant pays all the utilities, I personally would not charge more because you are renting them the house-not based on how many people are living there. 

So any person that comes your way, you evaluate them based off the probability of the listing being closed on(via representation as the buyer or seller, or both).Someone offering 10% under list isn't a tire kicker; they're looking to get the deal done.

Ft Myers Beach regulates the minimum stay to daily, weekly, and monthly based in the street the property is on.

Where are based out of?

You could have a case based on misrepresentation if the seller, acting as an agent, falsely claimed the roof leak was fixed.

Ceiling white matte, walls Navajo White eggshell, trim base white semi gloss. 

Best guess of his reason for selling is that he bought it low and during covid, stuffed every unit and room with a tenant on a month to month basis and now wants to sell at the max price based on the comps of the area.

The good news is the bigger the loan, the more more open the banks to lend you a non recourse loan, that means you dont need a guarantor in the US, they will underwrite based only on the property cashflow.