First, as others have pointed out, mediamatters.org has been outed by Project Veritas. It is not an independent website/organization.

Second, it is a blog site. Being a blog site, it can post anything it wants because it's not a news outlet. It's their personal beliefs, understanding, and/or opinions.

Third, I went to search for any evidence, sources, or studies where they received their information. I found absolutely nothing on their website that linked to any external sources. They never even said where they received this information from.