"...I think it is a muzzle brake and sound redirector..." A muzzle brake it is not. A brake redirects the gases coming out of the barrel through the holes it has. That thingy will not do that.
Might be the shroud for one of custommuzzlebrakes.com products, but alone it's nothing.
Likely that tight because manufacturers are always terrified of stuff coming loose. Even stuff that supposed to come loose. No logic involved so don't look for any. I'd put the thing in a padded vise, close to the forearm, and twist the firearm to get it off.