I think Seastorm was open last year? Not too sure, wasn't really paying attention to it...
The thing with Zoo Days is that it's specifically for the zoo, hence the name. The 2-3 rides they open are as a bonus if anything; the park isn't meant to open. Having Tomb Blaster open makes no sense, other than it being an indoor attraction, as it is away from all the zoo and it would be pointless for guests to walk round part of a park which has no rides open / winter maintenance to be done, just for one ride. Zufari construction has nothing to do with it, due to the fact Tomb Blaster has never open on Zoo Days (to my recollection at least).
With the opening of Zufari, there's access from Wanjama Village, so I don't see why any more of the park would need to be opened, though I guess if the park really want and maintenance wasn't required, it could be possible for them to open Tomb Blaster. I just don't see why they'd need to though?