To be fair, you said outright that he *could*, but that this didn't make
the art his. But what is the art? The individual pieces? The
arrangement? The exhibition? And when the curator is given free reign to
pick whatever pieces he likes for the exhibition, doesn't that begin to
blur the line a little? If I hand you a kumquat, a coconut, and a
banana, and say "put these on that chair", how you arrange them can say
something -- but your options are limited. But if I just tell you to put
three fruits on a chair, your selection of a kumquat, a coconut, and a
banana says something even before you set them down.
i think that the way most people see art exhibits can fall into two general categories that might refute this line of thinking.
1. people go to see an exhibit of one person's/group's work. that person's/group's work is the focus of the exhibit and the viewer. they don't mistake the curator for the work. they *might* like the way that the exhibit was put together (or not), but most don't even think of this stuff; they got to see the work of the name(s) on the exhibit.
2. people go to a museum and browse through the galleries until they find something they like and then view that work for a while. they take note of the artist and may file the name away for future reference. they aren't taking note of the curator.
now whether or not artists are excluded or put on a pedastel by this system is a totally different thing, but i think this is more a function of art criticism and history than it is of curating.