Nether Reactor

Same thing for me on Creative mode on my iPad (iOS 6.0.1) - tapping it just builds/breaks the block.

That is because you cannot run the reactor in creative mode. This was stated by Johan in his demonstration video last week. They will probably take the reactor items out of creative in a coming update.

Ah ok thanks for that! Any reason why not?

I can't recall him giving much of a reason, I just know it is supposed to be a feature only for survival for now. So that's why it breaks when you activate it in creative. It was not meant to be activated and i'm sure they will make that more clear in a future update.

I don't think this is necessarily resolved - the reporter didn't state that they were doing it in Creative (although it is highly likely).