You can think of it as a Monstrous Creature that can transport creatures like a vehicle. However, it doesn't say what happens to its cargo when it dies...
i don't think anything happens. i mean, you have to take a save when a vehicle blows up, but thats it, a bio titan doesn't blow up, so the troops it was transporting just disembark and the bio titan is taken off the board.
so they do have a forge world model? hmmm interesting...