Wow that guy is a pleasure to watch. California surfer here. Its true mostly mush here. I envy you guys ha ha. I was stationed in Okinawa many many years ago and surfed there. Im guessing it was more similar to Hawaii as it was all reef. I remember chest to shoulder high waves having so much power. When it got head high it would make me nervous ha ha. Ive never surfed Hawaii but would love to one day. Warm water! As for the young guy shortboard advise I think he will be ripping soon no matter what board he goes with.
yeah Hawaii's waves are pretty powerful even in the summer, I actually downsized to a 6'2 Sci fi 2.0 and absolutely shred on the board it feels so much more fun on a shortboard and it only took me a about 1hr to get used to the 1ft downsize and the 20 liters that was gone, and i thought being on a really small board in my eyes would be super hard but it was way easier than i thought even in 2-3ft Hawaii mush and my board has a medium entry and exit rocker so its even more surprising i can push it in mush (I'm the young guy)
for head high+ waves in Hawaii all u can do is not think about it and just go for it and try not to over think too much(thats what i do)the biggest wave i surfed was 7ft and it was a little scary but u get over it after your first wave