It is maybe a little condescending to expect all visitors are seasoned travelers ,of course there will be visitors experiencing travels outside their normal comfort zone! I believe she was apprehensive of this new experience and asked the guide if they had ever had someone bitten,of course this was bit traumatic!
Give the kid a break.
It is never a good idea to feed the marine life to entertain tourists. About 15 yrs ago they were doing this with the morays at Hol Chan and had several people bitten. Our daughter was.