Nah, you just remove the immobilizer as it's just a switch between the ECU and the starter circuit. And if you want to find a the key code, it's stamped on the tumblers in the lock, and your lock on the tank is simple to remove without causing visible damage.
But usually they don't sell the bike whole. They accrue less risk if they ditch the frame, and usually make more money parting it out. Some local sucker picks up a "salvage" frame for cheap and has some 'splaining to do when they try and re-title the bike. And the seller is nowhere to be found, of course.
EDIT: I know this because the previous owner of my bike had broken the alarm remote on his bike and so you had to be real careful starting the bike or the immobilizer would kick in and you'd have to screw with the key. Also the key was mangled so badly it barely worked, and wouldn't fit in the machine to have a copy made. I just removed the immobilizer, soldered the split wires together, and pulled the lock off the gas cap to get the code. The second locksmith I asked made me a key from the code only (wanted to see how easy that was.

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