Except part of Payton's "look at how awesome I am at sticking it to others" story was that the Saints offered to outbid Carolina, but the player refused because he already agreed to Carolina's deal and didn't want to go back on that. That's when the Saints traded back into the 7th to snipe him from Carolina.
The first rule about negotiating UDFA contracts before the draft is over is that you don't talk about negotiating UDFA contracts before the draft is over.