I think a Wonder should reflect the cultural highpoint of the civilization. I am not sure the destruction of a structure of another civilization is a highpoint. The Grove of Fetters would be a more appropriate candidate.
Imagine, the player spends 3500 resources and places the wonder in the most defensible location of the city, only to get the smoking ruins of a camp...
IMHO the ability to board is too generic to be accessible to one civ only, i would rather have it available for all civs with Romans having a bonus that enhances it.