Though our fortieth President, Ronald Reagan, ceased to be in 2004, his "100th birthday" was observed last year.
Werner von Braun expired in 1977, but still, last month, his "100th birthday" was noted.
As predicted by Bill Murray's character in Stripes, Tito Puente is now dead. And though you may HAVE been listening to him for years, and he WAS (and through his recordings, still is) fabulous, he joined the choir -- er, in this case, the Latin jazz band -- invisible in 2000. Still, we encountered a reference to his birthday today.
Only the living continue to age, as reflected by the increasing number of birthdays they have had.
A far more correct and appropriate phraseology is, "in memory of Great-Aunt Eliza on the 100th anniversary of her birth...." Or, you may feel free to "reflect on the accomplishments of the late Ezekiel Helmsworth-Cummings on the 85th anniversary of his birth."
Bonus: we dedicate things to the living using the phrase, "in honor of" and to the deceased with, "in memory of."
Supplemental Bonus: enjoy the Monty Python "Dead Parrot" sketch here.