Presumably someone dying in a disable toilet must be relatively rare
Someone dying in a public disabled toilet - very rare.
Someone collapsing in a disabled toilet - more common than you may think. There are many medical conditions, including heart attacks, where the first indicator of something amiss is an overwhelming desire to hurry to the loo.
Don't forget, either, that if we able-bodied people slip and fall over, we usually pick ourselves up, brush ourselves off and walk out. A disabled person who has fallen may not be able to get up without help. Together with the "false alarm", that is the most likely event one will encounter and if you are physically able to assist, please do.