I don't really need proof I don't think... they were made when Jenova arrived, they were released when the reunion was in progress and meteor had been summoned. I mean if Square bring out a new version it might have a special, glaringly obvious plot points pointed out by moogles option, but for now I'll rely on statistics and probabilties.
Why bother having the planet's main defence need to be summoned? The planet can summon the weapons on it's own.
