My insurance company won’t let me rent my 2 car garage or an office space that I have because it poses a “threat” of a non-tenant person coming onto the property and potentially posing harm to my residential tenants.

Giving your sister 250K of his equity and removing you from co-signing responsibility sounds great for you and your sister, but actually seems harmful financially to your nephew.

If you can and are willing to use bank debt, there's no harm in doing it.

They already caused the harm by losing the 1st deal.

This kind of indecision is harmful when running a business.

Think, the USDA brining armed feds to shut down Amish farmers for selling their unpasteurized milk, or the FDA allowing harmful chemical additives in our food that are banned in hundreds of other countries.

At a minimum you can have the satisfaction of knowing that the collection action will sit on their credit report for many years to come and may prevent them from harming another landlord.

You won't be upset if they don't feel like they aren't a good fit together"  No harm done and it just sets the expectations for you both and you know you did everything you could to get your point across.  

This action caused the property owner financial Harm.  

the reality is in situations like this when there Is massive litigation going on.. the very last thing your lawyer would have you do is get on Social media in any form.. its hunker down time for him.. full defense mode.. for those harmed its cry it to the ceilings to warn others.. with that much litigation something is going on its not just drama etc.. lawyers cant just file complaints without basis that's against the rules.