Pete Burtling is 31 so would have been sailing the AC50 at 25. James Spithill was 21 when he first sailed in the Amercia's Cup (well LV Cup) in 2000. Admittedly the IACC boats were not fast, but still, high load and high pressure. There would be thousands of kids sailing high performance foiling boats that could sail circles around most people on this forum.The AC75 Class is too expensive. That is becoming clearer by the Day.
As far as the AC40 is concerned @Chobani Sailor is right. Safety not a priority. I am not sure people under the age of 25 should be sailing these boats. They are a handful even for people like Burling, Tuke, Outteridge, Ashby or Davies.
If there is an age limit, it should be focused around the upper age limit and specifically related to Crash Bash Ben Ainsely. He seems to lack the reaction speed to handle fast boats safely.