Not how I'd want to do it for a track car - there is still a live feed from the battery to the alternator. So if there's a fuel leak, still a risk of fire. MSA would not like it.
The idea is that the battery is completely isolated.
Stopping the engine, and isolation/kill, are separate things.
I would always provide a dedicated and specific means to shut the engine down (remove power to the main relay, for example) that leaves a discharge path for the alternator and solenoid-type actuators. Then you can use the isolator on a stopped engine without issue.
Then you have to consider the "proper" use of the isolator/kill switch by a marshal. You might take the view that if you've had a crash, then stopping the engine and isolating the battery is the most important thing, to reduce the risk of fire and save your life, and that any risk of damage to the engine or ECU is secondary; perhaps irrelevant.
But since the isolator/kill might be used "just in case", after a minor incident, you may want to protect the engine/ecu from the risk of damage. In that case, a solid state type, with an ECU shutdown signal, that allows the ECU to stop the engine before the power is unceremoniously disconnected, is preferred.
This can be taken in as an engine enable signal to the ECU.
There are some very fancy (i.e. expensive) types that signal the ECU via CAN bus and allow a programmed and sequenced shut down, but I've not had first hand experience of these. But I do know someone who has successfully moved to one of these after destroying DBW outputs on an S8 2 or 3 times - they had been using a hybrid type, but with no shutdown signal to the ECU which, with hindsight, would probably have sorted the issue.