At a recent concert they had a jumbotron-type thing showing couples in the crowd. They happened to show a couple that was a CEO and his head of HR having an affair. Instead of keeping their cool, they both made it very clear they were A) together and B) shouldn't be, so the clip went viral. The tweet from Astronomer is his company reacting.

I'm not sure what that has to do with Scooby Doo. Maybe the joke is that Daphne is more typically seen as Fred's girl, or it's dependent on knowing the particular scene that picture is from.