The probability of being in Alternate or Direct Law AND the crew allowing the aircraft to get into the stall regime is minute
This might be a typical misconception, similar to what we see for system safety assessments sometimes.
The same reason why the aircraft has to revert to a different law might also cause the crew to do strange things. These events are
not necessarily independent. So in the end the probability of being in alternate Law might be exacly the same as the one one that a crew is confused. And it may both happen at the same time because of the same reason.
It needs to be very carefully evaluated, which failures are really independent (and their combination therefore highly remote), and which are resulting from a common cause or from each other, and hence are not so remote.
It is clear that we can not design aircraft for the combination of all possible events and conditions, but it should also be clear that we can not claim all events to be unrelated.
(1) A nose-down pitch that cannot be readily arrested
This is exactly the same misconception as the pilots had: when your aircraft drops its nose it wants to tell you something, and you should
not try to arrest this nose-down by pulling the stick all the way back, just to find that this does not arrest the movement.
Should Airbus provide tactile artificial stall warning in reversionary flight control laws?
Airbus reverts to other control laws, because the computers do no longer have all the data they need to identify that you leave your safe envelope. So by the nature of this, you may not be able to provide a stall warning in that situation. If the computer still would be able to fully understand the situation, it would still run in normal law.