It has become harder to find iOS apps in Google results these days, as some have noticed. Is this Google being anti-competitive toward is rival? No, just an issue on Apple's end that is out of Google's hands, according to the company.
When asked about why iTunes content appears to be ranking less well in search results these days, Google told Danny Sullivan at Search Engine Land:
We’ve been having some issues fetching pages from the iTunes web servers, and as a result some people may have had problems finding iTunes apps in search easily. We’re working with the team there to ensure search users can find what they’re looking for.
Matt Cutts has also been talking about it on Twitter:
@OurielOhayon I have high hopes, but this is the expected behavior when a web server returns 403 HTTP status code to Googlebot.