From your link
"Apple must review all apps in the App Store before making them available to users, ensuring that all apps are free from malware and other security threats."
In 2011, Charlie Miller, uploaded a non-harmful app to the App Store (as a proof of concept), it had the ability to steal data from users phones. He warned Apple about vulnerabilities. Rather than thanking him, they took away his developer licence.
Security researcher and ethical hacker Charlie Miller shattered the concept of iOS security yesterday (Nov. 7), revealing to the world that he'd gotten a malicious app approved by Apple and placed in the iTunes App Store.
www.nbcnews.com
When you say that apple won't allow a back- I guess you mean backdoor? Assuming that you use their iCloud backups, they will happily comply with court orders to hand those over. In China, they handed over stewardship of those back ups to a state owned telco. iCloud backups are encrypted, but as the gatekeepers of the encryption keys, it would be trivial for them to create phantom virtual devices that they could download the image to.
No internet enabled phone should be considered as "secure". It does however sound like you feel the need to believe that you are secure, so, what the hell, go for it.