No, I don't believe so. It has always been my understanding flash hiders broadley disburse gases at the muzzle and hence have a open architecture (example A2 birdcage). Compensators and brakes focus gases and have a channeled architecture, and in the example of this Athena device if anything the flash will be larger albeit focused forward.
But also I am of the mindset that if someone is examining your muzzle device to determine if it is a "flash hider" or not something has already gone horribly wrong and they are fishing for add-on charges. Honestly, I will make the effort to comply but it is not something I am going to spend too much time worrying about.
You might give it a try. Like I said I have not used it yet but the cost makes it easily worth giving in a try even if it does not work out. And again the quality of the machining is excellent.
Well actually the people to the side of you are not much in line with the ports. Someone standing behind you and about 15 degrees left/right of the axis of your point of aim might be a different story, like I said this is a very aggressive brake. No one complained and even if they did I'm a bit of a dick so I would probably just roll my eyes and keep on shooting.
The photo below where you can judge the angle of the ports gives you a better idea that it folks over your shoulder that might sense it the most.