Sale ended unsold. The seller has a large number of 'military' and 'vintage' items for sale, authenticity tbd.
Quoting from Matt Newsome's blog, "Sometime after WWII, the tartan woolen mills began to offer, along side the normal dark tartans, versions of those same tartans in lighter shades. They called them “ancient” because they were meant to represent what a piece of old, worn tartan, faded with age, might look like."
So if we agree the fabric was made as an ancient colors, then it most certainly would be a fraudulent military kilt.