I saw the still picture. It could be construed as a still taken in the middle of a spree of waving to make him look bad. But when you see a video clip like this GIF, there can be no doubt.
If I did this at work I would (and would deserve to) be fired. This was a pre-planned, practiced performance. It meant exactly what it appears to mean. https://mstdn.social/@Remittancegirl/113862818490772279