I would lose out in a month or two of rental income as I find new tenants after the treatment is done.

This is the prescription phase, where you show the Seller that your service is the best available treatment, taking all the factors of the Seller's situation into consideration for their pain.

I have an addendum that names the pet and details their responsibilities including instant repairs, licensing, flea treatment, etc.

@Dave Toelkes your correct it may be schedule C depending if he is considered a "dealer" in the business of buying and selling option contracts, but the better tax treatment in most case would be for him to be considered an "investor" not a "dealer" if he plans to hold the contract for more than a year and be taxed as capital gains.  

The most accurate picture will come from the form 8824 which your cpa files for the non-recognition treatment.  

Hopefully, the situation remedies it self now that we've had the pros come through.I hope you had the whole building treated and scheduled for another treatment in a month?!

If I needed medical treatment I would seek out a doctor.

To be able to use those or aerate you would essentially need to install a waste treatment plant (they do come in small sizes).

The issue is being able to separately track and manage the two sets of funds with different tax treatment.

If your intent was to flip the property then you did not have the intent to hold it for investment purposes and it wouldn't have met the qualified use test or qualified for 1031 exchange treatment.