It's cause the track has to shut down for a fire. Yes maybe they can figure out a way to get the burning EV bike off the track but if they can't get it out they probably still have to stay shut down for a while.
I used to go to lots of track days and have sat through both emergency medical shut-downs and fire & chemical spill shut-downs.
At least for motorcycles the way the race track works is you have a bunch of people who either pay for a track day or for race entries. Depending on how much they are willing to pay you either get 1 or 2 ambulances and EMT crews and you have a certain size fire crew and this has to be factored into the pricing.
If you have 1 EMT crew + ambulance and someone has an accident IME the track shuts down and no one can ride again until the ambulance returns from the hospital. While it's shut down all the customers are wasting money and considering whether they want to come back.
It's the same thing with a fire. But an ICE motorcycle doesn't take very long to put out and get off the track. If the EV takes even an hour to put the fire out and get it off the track it wrecks the schedule for the whole day as you have races or sessions that are shut down. IME an ICE fire was a 20 minute delay. That's one missed track day session or one race that has to be rescheduled (amateur races are short). A 1-hour EV fire would cancel 2+ races/sessions, and realistically do we actually think the EV fire is put out in 1 hour? ICE motorcycles go out on the track with barely any fuel at all, especially in races they go out with minimal fuel to save weight, so the fires go out quick.
A freaking small electric scooter caught fire recently, it took fire department few hours to even contain it, they were not able to actually put out flames.
Maybe less than ideal procedure, but electric stuff getting on fire is a massive risk and regulators recognize it as such, especially when not out in the open.
