Cowboy is using an injected perimeter on that piece, which means by definition it can be no thinner than 0.06 or 0.08 mm.

The only possible ventilation method for poly pieces thinner than that is v-looping (0.03 mm), which cowboy doesn't have.

So cowboy's poly perimeter is either 0.06 mm or 0.08 mm poly, either of which can take strong attachment.