I am learning that Jaguar appears to have designed their ECUs to live up to the reputation of British cars having terrible electrical/electronic systems. Worse, it appears deliberate.

It is as if their design protocol is to find the most ways and circumstances for the electronics to cripple and restrict the vehicles. I have only been exploring Jaguar a short time. But the volume of messages such as this and in other regards are starting to lead me to wonder if Jaguars are a very dangerous car to drive in a life-endangering ways - even setting aside performance, maintenance costs and shop-down-time inconveniences. In your instance, it was not the pothole that could kill you and others. But slowing you to 5 miles per hour is definitely life endangering programming in your car.