I guess we have different sources of information.
I'm a homeschooler, and our community has discussions re this topic fairly often (as we get unfairly criticized for many of the same reasons!)
Anyway, as far as I've been told, the term "helicopter parent" was coined by the college community to refer to the parents who can't cut the strings once their kid is away from home. Sometimes they even contact the professors via telephone or email to check up on assignments and/or to argue grades on behalf of their offspring. There was a very good article about it recently in either Newsweek or Time (can't remember which one because I read way too many articles, but I will try to find out). Colleges are really getting fed up with these parents. They are basically people who are so obsessed with their children's success that they can't bear to risk the children failing because for them it would be a personal failure.
[Excuse this part for being OT, but this topic drives me crazy because a lot of people compare homeschoolers to hoverers. My whole reason for homeschooling is to provide my child the ability to live her education as opposed to being confined to a classroom eight hours per day and reading about life in textbooks, not because I'm some kind of control freak who can't bear to let my kid out of my sight because I don't think she can handle things on her own.]
At any rate, that's one of the reasons I don't see CA as a helicopter. An enabler, yes...but I don't see a helicopter calling the police on her child, because that would put the dirty laundry out for public viewing. Of course, Caylee's existence must have complicated the mother-daughter dynamic to begin with, and perhaps at some point CA gave up her dreams for KC and pinned them all on Caylee...who knows, right?