How very sad.  Yes, obviously death eventually comes for each of us--Mahler constantly reminds us of this.  But almost always, the arrival is too soon for someone (or MANY "someones") 
Henry-Louis was the epitome of a scholar, with his unquenchable desire to learn more and more.  From my personal communications with him, I found him to be what was often said, in describing Gustav Mahler:  "a saintly person," though he would probably blush and protest at such a compliment, true as it is.
He lived the life he chose;  and we are richer for it.