Yea I think he will play off the bench at lock.
I don't think Benji will play 2 specialists hookers, so poor old Api will have to shoulder a lot of work.
Although, Latu coming on at lock is a middle, so I guess it's not crazy to have 2 front rowers, Latu as a lock (and halves cover) and TDS to interchange with Api. Bird starting at lock gives us cover outwide with injuries.
Really, if you have two 80 minute backrowers, you can definitely play that bench. Imagine the thrust through the middle bringing on Latu, TDS and Hunt at the same time against tiring forwards.
4 front rowers in the 17 is more than enough, so now that I think about it, I like having both Latu and TDS on the bench. With Bird in the team, we have everything covered.