I'm too young to be familiar with the gear, but I suspect it doesn't have velocity in terms of its own sound engine. At least, most classic organs don't have velocity; that's what the swell pedal is for.
Does it still pay attention to velocity and send that over MIDI? Well, it's impossible to send a MIDI Note On event without a velocity, but I'd think the organ would either send velocity based on the swell pedal position or just send a constant value *if* it doesn't detect velocity from the keyboard.
Really, you should be buying gear like this for its sound. I wouldn't even consider using it as a MIDI controller, given that good MIDI controllers are cheap, and thus, I wouldn't care about the velocity of outgoing MIDI data.