It’s up to the rider and his advisors IMO.Like a previous poster stated if you can ride a500cc speedway bike that’s the sport.I’ve seen many talented youngsters of his age .It’s a tough sport but you have to take the chances if they arise.Look at the Polish junior scene.
As a matter of interest how are crowds levels holding up nowadays,the standard of big name riders seems to have dropped ( that is not to say entertainment is less).?
Like you say it is a business decision and a bit of gamble.Time will tell,certainly effects my thoughts regarding regular attendance given fuel and other factors,including match day pricing.