And here's another one...
"So and so dies at 86."
Really? The word 'dies' is a verb. A dead person is not properly capable of a verb.
It should be "So and so is dead at 86."
Just sayin'.
The anniversary of one’s birth is a birthday, of course.
A dead person is still capable of a verb only while still alive. On the day of one’s death, the present tense form of the verb is the only time one is capable of it. But I see your point; perhaps the only proper way to express the event of death on the day of one’s death is the present indicative perfect tense (“have/has died”).