“This does not seem to me like a lot of water over 4 hours. His system should have been able to handle it”
Not true at all. It is not the ounces, which was about 96 ounces all together, it is the short span of time - just four hours. A daily amount for a grown man OVER 24 HOURS might be about 100 ounces. 96 ounces in just four hours, for an 11 year old, is like poisoning - the system cannot handle it.
OK.