Talk about encouraging pack behavior. 

In NC at least (you'll have to confirm with your state law and/or attorney) your behavior could be construed and classified as an attempt at retaliatory eviction (42-37.1.

Have you had experience included any of these “behavior” clauses in the lease to be explicit?

Another thing to consider when a prospect shows up to view the property they and possibly the kids will be on their best behavior.

Personally, I focus on mobile home parks, and although I have acquired thousands of properties across several other asset classes, the reason why I narrowed my focus to MHP is due their intrinsic recession resistant behavior. 

So much so that I'll bet if you ran a scenario and compared cost of incurring full tax on your sale vs savings from pay off of debt that you're almost a wash.The only counter point would be that our government has such a rich history of rewarding bad behavior when done by large groups of voting constituents that it would be a crying shame for you to be responsible and pay off your debt only to have the govt institute a large scale forgiveness policy.   

*Like bridges or skyscrapers designed to bear certain loads, stormwater management systems are conceived within the limits of expected behavior—such as rainfall or riverbank overrun events that might happen every 10 or 25 years.

Or do I explain to him that his behavior gives me reason to caution moving forward with payment?  

Unfortunately, enough examples of lender irresponsibility and outright immoral behavior do exist to, in the borrower's mind, justify their irresponsibility.

Tell the tenant you're frustrated by their behavior and you'd like them to go, meaning you'll let them out of the lease....that might shake them up a little.....or they might leave, even better.