While it is sad that another up and coming rider is lost, and of course, one can only sympathise with his family, the incident was unavoidable.
Tomizawa had a front end wash out on a fast corner and went down so fast it left Redding and De Angelis no where to go.
Scot Redding is recovering OK (last I heard) and his injuries are reportedly minor, and while Alex De Angelis received minor injuries he is having a very hard time dealing with the results of the crash.
He has been quoted as saying 'I tried to hit the bike ........ but it all happened too quickly', or words to that effect.
Our own Daryl Beatty is at Misano and has been doing the coverage for HD1 with Steve Parrish, both agreed that this was a 'racing incident' with a tragic outcome, but it is to be expected.
Caz,
DORNA regulations came into force several years ago in an effort to stop really young kids from entering the Grand Prix series.
IIRC the youngest age is 15 years and then the rider is only allowed to run in the 125 class.
After a couple of years on the small bikes the rider can step up to Moto2 (or the 'old' 250cc level as it used to be) and I'm not clear on the move to MotoGP age but I think it's around 18 or 19 years.
National rules are all over the place, but I think in Australia it is close to the DORNA regulations, even the dirt bikes are pretty well supervised.
The old caveat about motor sport is still as true today as it was decades ago, "Motor Racing Is Dangerous."