By putting this in the product description:
"every shot is met with a remarkably subdued report."
It will be deemed a silencer, regardless of actual efficacy.
The terms “firearm silencer” and “firearm muffler” mean any device for silencing,
muffling, or diminishing the report of a portable firearm, including any combination
of parts, designed or redesigned, and intended for use in assembling or fabricating
a firearm silencer or firearm muffler, and any part intended only for use in such
assembly or fabrication
So yeah, it's either ATF baiting or it's something legit that's gonna ensnare purchasers down the road.