Note the footprint. ‘sold contingent with 72 hour clause’
Translation: we want you suckers to remove all your contingencies within 72 hours so we can get this house off our backs. Um… yeah, that will work in this market. NOT!
I think maybe you misinterpreted what this meant. This means the seller has already agreed to accept an offer from a buyer, but the seller included a clause saying they can renege on that agreement if they get a better offer from you. The seller just have to give the original buyer 72 hours notice (aka 72 hr clause).
Generally, this is done when the offer that they accepted was from a buyer who still has to sell their current house.