"However the battery management system of the Roadster won't allow the car to reach that low level of charge."
I realize that you are quoting the article, but the owner's manual is simply not in agreement with this sentence.
From the Roadster 2/Roadster Sport owner's manual (italic emphasis is mine):
"Important! Caution: If the battery’s charge level falls to 0%, it must be plugged in immediately. Failure to do so can permanently damage the battery and this damage is not covered by the New Vehicle Limited Warranty. Also, if you allow the battery to fall to a critically low level it may not be possible to charge the vehicle. If you are unable to charge the vehicle, contact Tesla Motors."
[...]
"However, situations may arise in which you must leave the vehicle unplugged for an extended time (for example, at an airport when traveling for a couple of weeks). If this is the case, it is your responsibility to ensure that the battery does not become fully depleted."
[...]
"If for some reason, you are unable to keep the vehicle plugged in when it is not being used, it is up to you to preserve battery life by paying attention to the charge level and the temperature [...]"
The original article seemed to be stating or implying that the car's own on-board systems would continue to draw power well past the danger point, drastically reducing the time to destroy the battery.
This article seems to be stating that the car's systems will stop drawing power. The battery will continue to discharge in this situation, due to natural processes, but discharging to a point that destroys the battery takes much longer in that case.
This means there is still a risk that, if left unattended for extended periods (on the order of at least weeks, perhaps longer), the battery will become unusable. But this is not the same as the original claims which seemed to be arguing for design flaws which would hasten that process.
I realize that you are quoting the article, but the owner's manual is simply not in agreement with this sentence.
From the Roadster 2/Roadster Sport owner's manual (italic emphasis is mine):
"Important! Caution: If the battery’s charge level falls to 0%, it must be plugged in immediately. Failure to do so can permanently damage the battery and this damage is not covered by the New Vehicle Limited Warranty. Also, if you allow the battery to fall to a critically low level it may not be possible to charge the vehicle. If you are unable to charge the vehicle, contact Tesla Motors."
[...]
"However, situations may arise in which you must leave the vehicle unplugged for an extended time (for example, at an airport when traveling for a couple of weeks). If this is the case, it is your responsibility to ensure that the battery does not become fully depleted."
[...]
"If for some reason, you are unable to keep the vehicle plugged in when it is not being used, it is up to you to preserve battery life by paying attention to the charge level and the temperature [...]"