100% Not a lawyer, so this is absolutely not legal advice.
That being said, this would appear to be a brake with a blast directing shroud, similar to things like a Noveske PIG. It modifies the directional intensity of the sound, but it is not "designed or intended to muffle or stop the sound or report of a firearm", which is the wording defining suppressors as prohibited devices in the criminal code.
To my layperson's reading of the law, the SME would be legal.
As a shooter who's been beside some obnoxious brakes, I would certainly appreciate having them on the line beside me. Which means somewhere is a bureaucrat who thinks it should be illegal. Which means I wouldn't want to be the test case, as I'm not, once again, a lawyer, and those folks that are earn a much better salary than I.
Hopefully someone with better law-knowledge chimes in.