As for the big claim of rent abatement, the judge will likely disregard it.

If you are only screening tenants as good as a property manager is(meaning only on paper), then thats not good enough, it needs a personal touch. you can judge them on everything that is not a protected class, so why not judged them on what type of job they have, how they dress, what kind of car they drive, how they discipline their kids, their mannerisms etc. 

How will the bank look at my income and judge my DTI?

Assuming your brother went to court and told them he couldn't pay due to the shut down, I can't see any judge evicting a disabled veteran.

(With the 1031 exchange you will not have any cash from the sale and at least as much debt.)If so, they’ll just declare it on their taxes and pay the appropriate rate depending on their income level. 

You'll want to check your local landlord/tenant laws for what you can and cannot do with deposits and such, but it sounds like you can get a judgment levied against them for breach of lease and have a judge impose this judgment.

I forget the precise legal term for this, but basically the judge looks over your contract, examines what has actually happened, and then can overturn your deal using the "if it walks like a duck and quacks like a duck...it's a duck" principle. 

Keep a dated journal of your experience, install a security camera for video evidence.Make all interactions with him in writing, and always write your interaction as if a judge will read them 6 months later, don't antagonize or be passive aggressive, just factually state the problem and your reasonably requested solution, in a polite and neutral way.of course, none of that will probably work, but, it will be proof that you were reasonable and rational about the issues and it will probably show the neighbors antagonistic demeanor.Be real careful, that is real crazy to get a fan to intentionally blow smoke towards you.

@Tony Karns not having seen the property but judging by the description it is likely a waste of time to even sit down with the owner.

Alabama is hard to buy in, even the judges will admit they don't fully understand the law because it is ambiguous.