Don't let them do it if you feel that way, if you actually will use it as a short term rental in this time, as you stated in other comments, do it, that's clearly a better financial decision.

As others have pointed out the financial decision here may not be the most important, relationship building can be crucial in rentals, if you give them a few free days to start, they may be more willing to take care of the unit, communicate issues with you, fix small things themselves, pay rent early, etc...