I guess if you're going to stipulate that nobody believes anything Snowden says and that we're all sticking to the leaked Powerpoint slides, sure.
Google has motivation to bring clarity to their role in all of this. The NSA would rather keep everything secret. I'd believe Google more too...
Note that the slides have different degrees of redaction across sources. These links should together cover what's available on PRISM.
http://www.guardian.co.uk/world/2013/jun/06/us-tech-giants-n... http://www.washingtonpost.com/wp-srv/special/politics/prism-... http://www.guardian.co.uk/world/2013/jun/08/nsa-prism-server...