Originally Posted by OK465
Folks it is not necessary that speed change to change flight path angle up or down with thrust.
It is when the AoA is constant.
You're making the assumption AOA stays constant which is not true.
It is in alpha-protect mode because the FCS commands the elevator to maintain the AoA commanded by the sidestick position (leaving aside the phugoid damping terms, and the inclination of the thrust vector, to keep it simple).