I don't think it's any particular dislike of To'a, to be honest.
I think what we have here is To'a, Doueihi, Naden, Faataape & to a lesser extent Staines & Feledy all fighting out for what, really, should be 1 or 2 players spot.
If our starting centres next season are Olam & Bird, and your back-ups are Faataape & Doueihi, or Naden & To'a, or any other combination of 2 of the 4- you have good depth.
When you have 4 guys on relatively similar playing status, fighting for 2 back-up/fringe spots- you start thinking about value. To'a & Naden are the 2 most expensive of the 4. Makes sense that these would be the guys you look to move on.
The only thing that changes that is if one of them is scheduled to start- but then you still need to shift at least one of them. This isn't even taking into account low-cost Feledy being held back from playing time.
And that raises the bigger issue- a fringe 1st grade player is being relied upon to start. Of the 4, Doueihi is probably the most talented- and versatile. For mine, he's easily the better value player.