It is a label, but it has always been used by those expressing opposition to a policy that they label "trickle down". It has never been used by proponents of a policy to describe or advocate for their own policy.

The original comment, and many other comments spread across the Internet including yours, are written as if the elites themselves are the ones "advertising" the label of "trickle down economics" as if it's some kind of economic theory they are advocating for. But it's always been a label used by opponents, particularly Democrats to derogate Reagan era policies.