For one: players don't officially know who's in the team until Team List Tuesday, and it's not up to them where they play.
Second: they should know by now the sweet talk that gets romanced in contract negotiations dissipates the second they sign. Take Kotoni at 6, or future captain Payne, for example.
Third: Tesi, Selwyn, Herbie and Te Maire all have designs on that fullback role, whether they, like Herbie, announce it to the press or not. It's the most visible position on the field, comes with a pay rise and a certain level of glamour.
Fourth: Signing Walsh is clear sign to all prospective fullbacks that whatever the club told them about playing there, they had other plans.
Te Maire is the least connected to the club. He was already counting his days there. He's unlikely to stay.
Selwyn has time on his side. He's one of the top wingers in the country already. He can bide his time there, shift to centre or wait for injury. The club already has him locked up. They can do what they like. Selwyn, at this point, is happy to ride the wave.
Herbie is the biggest problem. He held a press conference to announce he only signed for a year at least partly because he wants the fullback position, and if he doesn't get it, he might not hang around. What he said in essence is he's unhappy playing centre for the Brisbane Broncos, and he's liable to hoof it. You'd have to expect he's ropeable right now.
Tesi would see his days are numbered. Unless he reads no social media, no press comments, and lives in a bubble, he would know all observers thought the team lifted several notches in his absence and no one wants him back at 1. He would see his only pathway back into the team through injury, and he would be behind Deine Mariner at centre/wing. He's no chance of playing fullback again, after this current stint.