Correct me if i'm wrong -
1. Drones cant feed themselves the workers do that.
2. Drones do from time to time visit other hives especially if there are queen cells or virgin queens in the hive.
So to your answer your question. No i don't think drones would be robbing. All those bees look like workers to me as well.
I had a problem with robing last week as well when i had a feeder like that. I bought a feeder to put in the hive instead solved the problem.
Side note: I'm better at spotting drones. I still haven't seen the queens in my hives and i'm just as bad at spotting eggs.