Dr. Sprague is speaking on commercial speech which is granted limited constitutional protection. How does this apply to social media?
The courts have not really defined commercial speech but they "Know it when they see it." Basically, anything coming out of an organization is commercial speech. Therefore, participating in a community (like an online community) ultimately to sell them a product even if the product is never mentioned is commercial speech. Blogging for a company is a commercial speech.
This means that the government can regulate what you say on the web. Be truthful about who you are. DO NOT BE DECEPTIVE! Tell people who you are. When you are involved with a product, your role changes in the "conversation".
Example is Marie Digby, a musician, who was thought to have appeared on a grassroots level through YouTube. However, it turns out that the whole thing was planned by a record company who told her to film herself in her living room. They are promoting her as a struggling, independent artist but actually has a record contract...they are being deceptive.