Take any agreements to the lawyer in case there are terms in the agreement that affect the remedies available to you.  

The property had a fire in the roof and has a little mold , but the scope of work includes remediation of both. 

Additionally, if the buyer fails to pay, the seller's remedy for non payment can be having to foreclose or a timeline equal to foreclosure so there is really no benefit. 

Its a common remedy, not a default under the lease.

Maybe get an estimate, ask him to pay 50% at close and remediate after purchase and the deal gets done.

If the profit is there, then yes.One thing to consider is proper remediation and being able to prove it. 

I suspect when you look back you will find you did the same.If you got an inspection on the property you may want to reach out to the inspector if anything was obvious but I don't think you will get any help there.You could also try to get an attorney to send a certified letter saying you are considering legal action if you can't come to a resolution but any additional fees may not be worth it.If I were in your shoes I would remedy the safety issues (electrical, plumbing, etc) with licensed contractors making them pull permits, consider this a lesson learned, and move on. 

We have a ton of radon here in PA so I submit in my reply if radon comes back high “Seller at sellers expense to install radon remediation system by ABC Radon Specialists and furnish receipts of completed work and satisfactory retesting of the radon level...” this way I know it’s my guy doing it and will be done right.

I know that this can be state specific too, but there will be quite a bit of work being done and that could be a case for remediation which seems very expensive.

Is there anything that I can do to remedy the hit of having to get flood insurance?