For what it’s worth, this is my take on it (from experience)
In theory you are correct, the aircraft is supposed to protect you from an overspeed condition, however a go around with a low altitude level-off can turn into an overspeed very quickly, if you get behind the aircraft.
It’s because you are putting in a bootload of thrust (energy) in at low speed. It will initially go into srs, and pitch up significantly to maintain the srs speed target (hence a massive rate of climb) , followed very soon by alt* to level off.
Everything is essentially happening at once and you’re in alt* before you know it.
If you don’t bring the thrust back to climb pretty quicky (which will engage the autothrust) you will accelerate rapidly and if old mate is a bit slow getting the flaps retracted you will overspeed.
Seen it happen in the sim (and done it myself during endorsement training)
