No it's not, forums were around on the internet long before the term "social media" existed. Same with comments on a newspaper article, they are not social media.
Just because the term "social media" came later and was popularised by certain kinds of social media networks, it doesn't mean it doesn't encompass regular old fashioned forums too.
What is this right now other than a social interaction about a piece of media (the article)? This is a very arbitrary distinction for you to draw.