Right, but in the absence of any platform that satisfactorily answers all concerns, the best you can do is look at what choices actually expose you to more threats. Apple has a pretty good track record, and are straightforwardly financially motivated to keep malware off your phone.
(Plus: since you always implicitly trust your hardware vendor, in the case of Apple, it is moot whether you trust the OS vendor anyway)
(Also: with the means to look for malware, there is no way to be sure)
