Actually:
http://www.wish.org/about/our_mission
Since 1980, the Make-A-Wish Foundation® has enriched the lives of children with life-threatening medical conditions through its wish-granting work.
Not to make light of a child with cancer, but according to his mother he is in remission and will finish treatment this June. I don't believe he is terminal.
http://www.angelsforenzo.com/
I don't know that she "signed up" for anything. I think she has been a supporter in some way, which leads the MAWF to consider her a "friend." Even now.
While it would have been nice for her to meet with him, the article I linked earlier by a person who had volunteered with MAWF says that wishes are turned down all the time by celebrities, but it doesn't make the news. For this reason, families are encouraged not to pick this type of wish b/c it is so hard to make happen. This makes the author (and me) wonder who leaked it, why the general media isn't picking it up, and what motives are involved.