Just paranoa in my opinion. Before digital, nobody ever thought about trigger voltages being too high for cameras.
I think the main worry camera manufacturers have is if a charged flash is put into the hot shoe and the centre pin momentarily comes into contact with one of the other contacts (which is just about impossible anyway).
A modern camera will have an opto-triac to trigger the flash and you would have no luck trying to find one which is only rated at six volts (the common mythical 'safe' voltage).
On top of that, why would you bother designing a camera which could be destroyed by a high voltage flash when the circuitry required to prevent it costs almost nothing?
The safest thing to do is find a manual and read its specifications. When the Minolta 9000 was new, high voltage triggered flashes were in common use and I would be very surprised if the camera could not handle them.
Steve.