It is INTERESTING that Cindy would provide a shared brush with knowledge of another brush used only by Caylee being readily available. Is it probative? In a word, yes. It substantiates that while Cindy has publicly stated that she has done what she could to find her granddaughter and LE has done nothing, this is one instance where the work she made LE do was made difficult, and in the findings, proved only that the two hair samples were from related people. It tests the statements Cindy has made to demonstrate a likeliness for self-serving answers.
Is it criminal? I don't believe so. LE got a brush and performed tests on it which conclusively and with "statistical certainty" states the hair belongs to someone with the MtDNA of Cindy Anthony. We are then back to Cindy, her mother, her daughter and her son are all still accounted for, and only one person who shares this MtDNA is not.
Chilly is correct in one aspect: Criminally, Cindy did nothing wrong. Whoever it was waaaaaaay back earlier on who said it then became a matter of the SPIRIT of the law in Cindy complying is also correct. Cindy admits to not getting a brush she knows would be more beneficial to LE, but she DID provide one, so what's the big deal?
It comes down to how helpful is she truly being, considering her self-serving behavior as well as the protective statements of adoration she makes about her daughter. And sadly, she is not very helpful at all in the search for her granddaughter, and that my friends, is the bottom line.