Don't think I buy the argument (as you've summarized it) that the memorial service etc. is no longer about the Journey. But even if it is, that doesn't make it a symbol standing in for an event; it's just a different event: a memorial rather than adding significance to Aunt Mildred's Journey.

As you pointed out a while ago, my notion of "symbol" when I was writing "symbol stands in for the event" isn't the richest notion one can use. In any event, it's more along the lines of "By using the word 'marketing' he thinks he's making a socioeconomic analysis, but all he's doing is waving a buzzword." My concept is actually pretty crude.