I am puzzled by the choice made to inhibit min speed protection with AP or FD engaged and FLCH selected with Throttle 'HOLD'.
Minimalist design philosophy? Obviously, if the AP is engaged, speed well never decay, as the AP will lower the nose to maintain, until it hits altitude capture (or whatever it's called), then the ATS comes alive. One could argue similarly with the FD engaged; if pilot is hand-flying it is a reasonable assumption that he/she would be following the FD, which would also be commanding a nose-down to attain/retain speed.
Now if the AP and FD are off or FD ignored (dunno if exactly relevant to the 777) and pilot pulls back on stick, the AT does not react and speed decreases. This happens in my machine (not a real Boeing) when it is in equivalent of FLCH. Speed will reduce BUT, when Vmin is reached, even if the ATS is off, Lo Speed Protection engages, ATS comes alive and controls to Vmin. A similar function appears to be fitted to Airbii. Not so, it seems, 777 or by the sounds of it 787?
This, from the CNN article, will answer your question, BOAC:
Boeing said it was without fault.
"All airplane systems were functioning as expected prior to impact and did not contribute to the accident," it told the safety board.
Asked why the "hold" mode did not protect against dangerous drop-offs in speed, Boeing told the board, "To do this would violate (Boeing's) design philosophy: the pilot is the final authority for the operation of the airplane."
"If the auto-throttle automatically (switched mode to prevent an aerodynamic stall), it would be overriding the crew's selection," Boeing said.