Since the Simulator is a program running on an Intel Macintosh (or
(although this isn't documented) a PowerPC Macintosh) and an iPhone
has an Arm processor (entirely different instruction set) the app from
the store will never work, even if there were not code signing issues.
You might try writing to the author and asking for a Simulator
version. Since the App is free, they might send it to you. But don't
get hurt feelings if they don't.