That sounds pretty cool, but I’m afraid it would become complex to, on top on specifying that some track is locked down, to specify when you add an overdub if it has to be locked down too, or not. And don’t forget you should then even have to consider already existing overdubs when you decide to lock a track down… Unless you see a nice and easy way to do this without triple-or-more clicks (don’t forget the 6x6 use case too…), I’m afraid it would be too complex.
The locking down mechanism has to be simple, and it would probably trigger far less switches clicks if anything present in a track (including all existing and future overdubs) is locked down too if the track is locked down. To summarize, I think regarding that feature, that a track and its overdubs has to be considered as a single entity, meaning that if you add an overdub to a locked down track it spans automatically to other parts.
Then if you need to do something specific to a part, it probably has to be on a separated track, maybe at the cost of having to switch to 6x6 in some cases.
What do you think ?
Nevertheless, it has been already mentioned by @DavidPackouz (and @BrennanSingularSound too in this thread) that the feature is already in the pipe, and maybe we are discussing about something they already designed and partly implemented…