I think if there is any possibility of it create a health hazard (even a small one) I would address immediately. 

Now they repeatedly threatened with a lawyers demand letter inhabitable health issues for mold and other issues. 

Do one or both for the education and modify as you learn and build wealth -one thing for sure is it is not static  it changes with age, health, laws, technology, family situations, etc   Taxation, succession plan, estate plan, insurance etc may all play a role.

@Luke Petro,Try contacting the local health department inspector, buy them a cup of coffee and see their experience with exterminators.  

One call to the local health board would have answered this question

.- There are health concerns with demolition.

Be strategic of course.Beyond that consider transportation, power, financing, broadcasting, health and fitness, land use, hospitality, advertising, and storage ideas.

As much as I didn't want an employee I need one for the health insurance in my state to get the benefits my family needs (long story and ****** state law changes).

Even solid people can be annoying renters -- poor cleanliness over the course of a year is frustrating, over 5 years it could turn into hoarding, health hazard, or damage to your property.  

His health no longer lets him do this.