Update: I spoke with the tenants and they agreed to pay for half of the mold test - this was their suggestion and I accepted their offer.
Unfortunately mold tests do not say whether a space is inhabitable or not....they only reveal what types of mold and their spore count.
However, there is more good news. As long as a room does not have any source of water coming in AND the humidity of the room is less than 50%, then mold cannot grow. This won't help with the mold air quality test, but it does ensure that the room should not have any future mold issues.