What would be the purpose of such a bot? I don't see how it could be used usefully. I mean margin trading costs fees and they are high on bitfinex. So i wonder where you see the problem.
I do not claim such a bot exists. Just saying it is a possibility, as this "taking an offer, returning the money within 1 minute" seems to be very persistent. Since it is possible to hold lender's money without paying interest, it is possible to automate the process. Benefit: shorting for free.
So i wonder where you see the problem
If you do not see any problem with this, please lend me some money. I will hold your money, but will not pay any interest. From lenders' point of view this is definitely a problem.
You would short for free... for one minute. What's in it for you then? It's not that you can earn money by doing that. In fact you will lose money when you use it for trading.
The only advantage one could get with that might be clearing out the loans so that your own, higher priced, loan will be taken.
But for shorting it sounds useless.