The post says it right there. X86 is harder to emulate than PPC (which has been done before, Dolphin)
The problem with that argument is that eventually, knowing enough about how the original hardware works, you could even not need to do it at all.
Ideal scenario: you don't emulate a x86 if you are running a x86, you filter that subset of instructions that don't work natively and use some sort of "interpreter" to translate them.
Not every emulator needs to go "in the byuu's way" replicating the hardware perfectly via software.
In fact, that's a damn inefficient way to do it which a developer should consider only if:
1- he values perfect accuracy above any other metric
2- he has a very detailed documentation of the original hardware
3- he has a lot (A LOT) of surplus power to spare.