RetiredF4
When pitch is established (lets sáy 10°) and the aircraft is decelerating, the body would feel a descending sensation even if still climbing.
But wouldn't the Captain have noticed the sustained, unusual attitude? As the person ultimately in charge of the flight, going through the ITCZ with two youngsters up front, he could be expected to pay a bit of attention. The PNF must have thought it possible to get to the flight deck, or he wouldn't have been so annoyed they were on their own.
Rockhound
The rough ride - be it due to weather, stall, whatever - was sufficiently intense to alarm the cabin crew, who called the flight deck on several occasions, at 2:10:55.9, 2:10:59.4, 2:11:02.3, and 2:11:24.9, each time without receiving a response.
It appears the crew was more concerned than the Captain.