I believe that releasing the tenants from their leases without consulting you has done your investment harm and was done without just cause if your rendition of the scenario is accurate.

. - Sounds like a phone call to your lawyer is worth the time to see what legal options you might have if they don't take it down.That sounds like overkill for something that just feels ethically wrong but isn't actually harming me.

It would be hard for a SFR owner to use any of those reasons without proof of how it harms them. 

If I personally, as a fact, screwed up and caused somebody harm, then I have to take responsibility for my own stupid actions.

I would be cautious of using rat poison at a property due to liability (harming tenants, pets, etc.).

- How to deal with tenants who can't or won't follow a standard work order process- How handle periodic maintenance inspections and if the tenant is causing harm to the unit/causing the issue?

It will make no harm to call one licensed contractor to give you a quote and then learn from them.  

However, if you rent the place right away you'd technically have no harm as a result of the broke.

You cannot ask for higher deposit or pet fee or pet rent, and you cannot ask what their medical condition is, but I don't see any harm in telling them up front that  you have an issue that would be an undue burden on you.

Also if they pose a real not hypothetical risk of harm or damage.