If you wish to imply the issue is due to my lack of understanding then go right ahead, but at least first explain why what I said is wrong.
A lot of people get their apps from the app stores on Android/iOS/etc. App stores do not provide the raw source and let you compile it last time I checked. So in order for OSS to provide a security advantage over closed source you'd have to sideload your apps after doing the inspection and compilation stages yourself (or having a trusted third party do it).
People throw the "open source so secure" justification around all the time, it is rarely justified. Really you aren't trusting OSS, you're trusting third parties who inspect the code on your behalf (e.g. distro' vendors in the Linux world). In the app world there are no third parties doing the verification step for you, unless you count Apple.