Why would PZ write up a post on what they didn't find?
And in the past they've definitely written posts on issues that only affect Android (as far as mobile goes), like their super deep dive into remote broadcom wireless exploits.
https://googleprojectzero.blogspot.com/2017/04/over-air-expl...
Probably not a great example, given that Broadcom bugs affect anyone using Broadcom, which, yep, includes iPhones:
> A partial list of devices which make use of this platform includes the Nexus 5, 6 and 6P, most Samsung flagship devices, and all iPhones since the iPhone 4.
And the 5 post write up on the PZ blog.
Security with mobile devices is definitely a don't throw stones in glass houses situation.