iOS has a lot of layers and mitigations both in software and proprietary hardware that aren't found in other systems. Keep in mind that this story would be 20 % the length on other systems, because "physical memory read/write primitive" would be a total break.
I should note that PPL is not designed to protect against the kinds of attack described in this article; it's really meant to prevent substitution of forged page tables and by coincidence the address chosen by the author ended up being unmappable due to an attempt to protect against virtual memory read/write in the kernel.
