If it happened more often I might take the time to file the paper work, which is sounds like she finally just did.
I agree with your point about filing the paperwork, but if the TSA maintains that no kids are on the watch list, why are agents subjecting kids to the process?
The original NY Times article has more detail. In particular:
The first time he was patted down, at Newark Liberty International Airport, Mikey was 2. He cried.
After years of long delays and waits for supervisors at every airport ticket counter, this year’s vacation to the Bahamas badly shook up the family. Mikey was frisked on the way there, then more aggressively on the way home.
"Up your arms, down your arms, up your crotch - someone is patting your 8-year-old down like he’s a criminal," Mrs. Hicks recounted. "A terrorist can blow his underwear up and they don’t catch him. But my 8-year-old can’t walk through security without being frisked."
http://www.nytimes.com/2010/01/14/nyregion/14watchlist.html
With that context, its a lot easier to understand her frustration.