"If you chose the Apple ecosystem because you don't trust Google – bad news." Some/many choose Apple not because they don't trust Google's infrastructure, but because of what they do with the data. Just because AAPL uses Google (or Azure or AWS) as a big honking, distributed disk doesn't mean Google gets its hands on decrypted data.
Apple's just being smart: as with their hardware suppliers, they're letting cloud providers compete against each other to get Apple the best price for what is essentially a commodity by now.
As an aside, I thought I read a year or so ago that this is all temporary as Apple is building out its own server farms. Aren't some of their services already on Apple servers (e.g. the App Store, videos, music, etc.?)