Re: Hmm, so we have to trust Apple not to get pwned?
If this service got pwned, someone would get access to IP addresses of safe browsing queries. Oh noes!
Who would you rather have get their hands on this data, some hackers who can do nothing with just your IP address and a one way hash of the URL you're visiting, or Google who almost certainly has a massive mountain of data on you from thousands of sources both online and in meatspace they can correlate it against?
There's also a risk of Google's service getting pwned, and since proxy software is simpler it is probably less likely of the two for that to happen.