I think the supposed intent was to get them early via the relocator function at Castelia, and breed them for trade. The daycare function’s obtained relatively early in BW, and the Zoroark line is Field, so it’s easy to breed with most of the early game Pokémon. Both Zorua’s and Zoroark’s events happen around early-midgame regardless (Zorua is a giveaway, Zoroark is slightly later after reaching Nimbasa and taking a detour), but the real problem is really just how hard it was for the international players to get ahold of him through direct trade since 1. event distributions are handled much differently abroad than in an extremely packed country like Japan, 2. the GTS at the time had no internal manual name-search function, and 3. the much broader distribution of players and slim likelihood that they had to have owned a copy of Gen IV, attended an event, then thought to breed it in the first place being incredibly specific and slim.
I think the real problem is TPCi trying to work a game specifically made for JP audiences to the western crowd in the first place; it’s really evident in the backwards way specific communications features like Join Avenue and Entralink/Funfest work; the former’s a sort of proto-StreetPass that operates similarly to TWEWY’s Mingle mode, the latter being a resource light multiplayer mode that’s able to support 100 simultaneous players (good luck hitting that cap anywhere other than Japan).