From what I understand/see, Aleva Hifo doesn't have any sort of contract, non-guaranteed or otherwise. He was invited to walk into Saints mini-camp and show what he could do and possibly earn a contract, but that's it. This isn't Micah Simon (who has a 3 year min contract with no guarantees and could be cut at any time).
So it's up to you whether Hifo should be added to "Cougars in the NFL" or not. Frankly, I have no issue either way. But if Hifo's included, then that means there's some others who have opportunities to show up at camps without contracts. Kavika Fonua has an invite to show up at Panthers camp.