A conversation with 
The Open Graph Protocol was established in 2010 by Facebook to streamline the publication of images. The OG Tags in the meta section of a page defines an object. Sites like facebook will embed this object (which contains the image) on their site when people link to a URL.
The image above reveals the HTML source from the page [ogp.me]. Ogp.me is an official site for this standard. The OG data includes a link to the image at ogp.me/logo.png which happens to be the project's logo:
If I put a link on Facebook to this page, Facebook would publish an object on the page which includes the image.
I find the Open Graph Protocol frustrating because it does not clarify the copyright status of the image used in the Open Graph object.
The OG Protocol clearly creates an object designed for use on multiple sites. Facebook, Google and Twitter interpret the code this way.
Does including a link to an image in an Open Graph Object release the image into the public domain? Did OGP release their corporate logo into the public domain when they added the URL to their logo on their homepage?
The HIVE specific question is: Can I use images referenced with an OG meta tag as the primary image for my post? Or should #hivewathers and 
I would like to point out that hive.blog publishes OG meta tags which contain a link to the primary images for a post. When you share a link from HIVE on other social media sites, these sites embed the object created by the meta tag.
My inclination is to say that the Open Graph Protocol simply gives sites the rights to use the object listed in the meta tag. The OG Protocol does not release the image into the public domain. Therefore HIVE publishers should not use the image as the primary image for their post.
As a side note: It seems to me that the best approach that sites like HIVE should take to the OG protocol would be for HIVE to read referenced sites. If the site has OG tags, HIVE could make a little mouse over link that showed the image.