Note, this is an iOS issue only. There are numerous MAME emulators for OS X.
Also, all they did was ban it from the iOS App Store. A jailbroken iPhone or iPad would probably still be able to run it. In fact, the program was originally intended for jailbroken devices:
"iMAME4all is a iOS universal app done by David Valdeita (Seleuco), port of MAME 0.37b5 emulator by Nicola Salmoria & TEAM for all jailbroken iOS devices (iPad HD, iPhone 4G , iPod touch and older) and it is based on GP2X, WIZ MAME4ALL 2.5 by Franxis."