I'm a freeediver. Never heard of secondary drowning. What we call 'fainting spells' can happen while training for freediving. The guy could have been doing that unsupervised, which is a big no no. But when we train or compete we're not that tense about fainting spells. We don't like it, try to avoid them... They happen when people get further than their limits, and as training is about coming closer to your limits, well... After them if people come back 'normally' (I know it doesn't seem normal at all to you, but if it takes less than 10 secs), people don't go to hospital. They are chastised by a coach or referee and suffer a little shame. First thing you learn while training for static apnea is how to know when your buddy is overdoing it and what to do then. I've never had a fainting spell or what we call samba (violent shaking, which is the first sign that you've gone too far) but I don't know if people inhale water in that case. I'll certainly ask my coach about secondary drowning next time. Of course, not knowing who the guy was and what he was doing, you were very right to take him to hospital, but I'd agree the explanation why he had to got was maybe a little late...