A Klingon was also able to use the Orb of Time in "Trials and Tribble-ations".
It seems the Prophets don't take the race into account when it comes to choosing to whom to send a vision, but much more the fate of the person using it, in other terms : the Plot !
Although Prophet's Motive would tend to indicate that opening an orb in the wormhole forces them to communicate.
"The main difference between Trekkies and Manchester United fans is that Trekkies never trashed a train carriage. So why are the Trekkies the social outcasts?"
Terry Pratchett