Edit: Well, I'll be! So you can. I was completely oblivious!
I suppose it's no different from Infinity Blade, though. If you want to reduce your enjoyment and your disposable real life income in one fell swoop, there's an option for that.
I've played a lot of freemium games on the iPad and I'd honestly still not consider Galaxy On Fire II (or Infinity Blade, for that matter) to fall under that banner because paying for ingame currency in both cases actively undermines the point of the game; as opposed to the hundreds of "free" games which don't really get fun until you unlock their content.