For some expansion on your points, in the example you give then pulling the thrust levers back to idle will disconnect autothrust obviously, so Vls won't have any great practical implication in that phase of flight for by definition it's merely the lowest selectable speed with autothrust on. Speed then further decays down the amber band towards V alpha prot, where the sidestick now commands changes in alpha. Given the autopilot is still in ALT mode then it'll keep pulling back until alpha reaches alpha prot plus one degree, at which point the autopilot will disconnect. If the stick is left alone, as far as I understand it, the "aft stick input" made by the autopilot since speed decayed below V alpha prot will now be released and IIRC auto trimming will also have ceased then so the aircraft will nose over to maintain V alpha prot which is the trimmed state. To further reduce speed then aft stick must be introduced. As long as autothrust is serviceable then it'll intervene in alpha floor mode (not entirely certain what it's trigger is, think it depends on pitch rate amongst other things) and you'll get into TOGA lock. However if you disconnect autothrust at the onset of alpha floor then you should be allowed to fly merrily down to V alpha max. Any further aft stick input will be ignored essentially and the aircraft descends at V alpha max. Willing to stand corrected of course on any of that but that's how I understand it.