From an immediacy standpoint, if you find one of these situations, you should notify the PM of the mistake and ask for them to please update the profile appropriately. Typically these are honest mistakes and not intended to cause issues, even though the scenarios you mention above are conceivable. If the PM either is idle or slow to respond, you might just email the admins at info (at our address, wikitree.com) and ask for their assistance.
The policy on Living People is here. In most cases, profiles marked appropriately would be unlisted. However, in this case, this is most likely a simple mistake and someone presumed she had passed due to her age.
I don't believe we have an explicit policy that states that if a person is less than a certain age with no absolute proof of death that they must be listed as living, but there are general guidelines that various people follow. For example, UK Census data is held as private for 100 years. In Canada it is 92 years. In the US it is 72 years. So data being made public varies in different countries. In general, I'd imagine most people begin making assumptions around the age of 90+, with 100+ being even more likely, and from what I've seen, only in very rare circumstances would someone imagine that someone 110+ is still living. However, the oldest living person alive today is 119 years old, so in some cases, these assumptions are incorrect.
Regardless, I would simply ask for the mistake to be corrected, but it is an interesting proposition as to what date we should set as a general "guideline" for new or amateur genealogists to follow when guessimating whether a person is still living or not.
