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.