Direct from the horse’s mouth: https://www.ubisoft.com/en-us/help/account/article/closure-of-inactive-ubisoft-accounts/000079595
Edit: The Ubisoft page linked here has almost completely changed in the last day.
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Even then, deceased people’s accounts can go to their next of kin. GOG does this with provided legal documentations and will.
That is true. I will agree that the wording seems deliberately kept vague.