Nice people from Yoast added SNAP to the list of incompatible plugins without any additional explanation.
The following plugins might cause (open graph) issues with Yoast WordPress SEO: NextScripts: Social Networks Auto-Poster
Since there is no way to contact them, here is the explanation:
You can’t have more then one set of open graph tags on your site. Yoast SEO Plugin has an ability to add open graph tags on your site and SNAP can add open graph tags to your site as well. If you have both features active you will get two sets of open graph tags and that will confuse social networks that use open graph tags.
You need to disable open graph tags in one of the plugins.
UPD (Dec 3, 2014):
We reached out to Yoast, explained the situation and they agreed that there is no conflict between Yoast and SNAP: https://github.com/Yoast/wordpress-seo/issues/1796