It's not just the iOS API and OpenGL adaption, the quality of J2ObjC's code conversion is in question as well so the conversion may introduce many problems that may be difficult and tiresome to track down. Plus any future changes done in jPCT-AE would need to be duplicated in jPCT-iOS, tested, patched, etc..
I mean it would be nice having an iOS version but I've had to convert a large amount of code from one platform to another (C++ MFC to C# .NET) and was something that introduced a lot hair pulling and headaches :p