Even if Tobi=Shisui in the movie, there are two things that don't necessarily make it so in manga canon:
- This is a movie that is pretty much an Alternative Universe adaptation. So, if in an AU Tobi=Shisui, maybe in canon it isn't.
- Why the fuck would Kishi reveal Tobi in a movie first instead of the manga? I think Kishi is simply having fun writing it and exploring possibilities that he CAN'T do in the manga canon, so probably Tobi is someone else in canon.
Edit: and 3) It could be a troll, either from the translator or from the Japanese source.