They made the movie full aware that Tsunami are a real thing, but it never becomes a problem not until a recent event occurs. I haven't seen the film but I am pretty sure it's not sensationalist popcorn stuff. The studio still wants the film to do as well as it possibly can at the box office and that Japanese would be way too traumatized right now to go and see something like this. So they delay it.

I remember how I thought I'd never be able to enjoy a terrorist attack action film after 9/11, but of course the time that passed remedied that. It may not have been the case for people much more involved in the events than me, though.