Well, in my opinion, whether somebody alive or not is something very real and tangible (albeit, 't is best to let some time pass first, you know know when a clinically dead person might come back to life
. Wether being dead is possible because it's 'impossible to have properties whilst dead' is a matter of semantics in my opinion. It doesn't change the fact that the organism no longer functions and decays.
Not having something also means having the opposite. Something can easily posses the quality of not possing a certain quality.
I think the reason Zen doesn't use words is because of this sort of semantics. If you agree with the statement: "He is not alive." You do so because you agree with the statement "He does not posses the properties needed to be alive". This means "He is dead". That's just how we use language. It's a grammatical issue imo.