In this process the system makes no qualitative judgement about which TL is forgotten, and which is correct or etc.
Of course you are right. I expressed my logic in far too simplistic terms. The decision , the qualitative judgement was of course made by the designers of the system. And they did decide that in such a set of circumstances (ATHR disconnect while TL in CLB or MCT) it is much more probable that the pilot has not yet had the time to move the lever to a desired thrust setting - hence the Thrust Lock.
Your logic presupposes that the thrust lever that moved (or appears to have moved) is the one that is expressing the pilot's intention.
Actually, no. My logic is focused on the fact that the designers have designed in a state which assumes that in some specific (Thrust Lock) cases the TL does not (yet) represent the demands of a pilot.
Any system that would automatically trigger spoiler and autobrake functions (let alone the other engine to idle as was suggested) in response to a single TL in reverse signal on ground (2 engines operating) assumes both that signal is valid (and that there is an ECAM procedure for uncommanded Rev deployment tells you there is a sufficiently high statistical probability that it may not be) and that the pilot's decision will always be to stop. Neither supposition is always true.
But that was not what I was suggesting. I was NOT suggesting that one TL lever in reverse on ground should always engage reversers, spoilers and autobrakes.
My suggestion was that as the Thrust Lock state of a thrust lever effectively means that the system considers the position of that lever to be "invalid" in a sense that it does not (yet) represent power demands, that ONLY in case of one TL being in a Thrust Lock (ignored) state should the system also ignore that lever in regards to preventing spoilers and autobrakes from deploying. I.e. only if one lever is in Thrust Locked state should the system act on the other lever alone.
The logic is that double faults are extremely unlikely. Thrust Lock state is already essentially a failure scenario. Either a failure of a machine - or in this instance of a man. It is highly unlikely that in the case of Thrust Lock engaging, the other thrust lever sensors also fail.
Extending Thrust Lock so that it would not just lock the thrust but also ignore that lever position as determinant in actioning logic would definitely not kill you in RTO or go around situations. Because it isn't possible for Thrust Lock to activate in those situations.