You are right, because RK found Caylee's remains, he could have looked in the bag and touched. But, RK was very definitive in his LE interview. He insisted that he didn't "
touch" anything at the remains scene.OCSO pressed him pretty hard too. And RK said that he ONLY used his worker's stick to poke. He specifically said he didn't touch anything.
So, there is opportunity for Casey's defense should RK have not been forthcoming about what he did when he found Caylee's remains.
ICA & George & Cindy were Caylee's caretakers, you'd expect them to dress her, change her diapers, carry and touch the bag that held Caylee's toys. Finding their DNA on Caylee's pants or the ball/laundry bag would not mean anything sinister. After 6 months in the swamp and being wrapped in plastic for days in the trunk of Casey's car their DNA would be degraded and easily contaminated.
Anybody who touched the shorts and bag just before or while they were collected could contaminate them. We know traces of a lab worker's DNA was picked up during less sensitive testing of the duct tape.
I think further DNA testing is a smart move by the defense. It makes it look like ICA is looking for the "real killer" and like she isn't afraid of scientific results. There is no risk. You'd expect to find the mother's DNA on her toddler's clothes or toy bag. Any foreign DNA is an opportunity to point the finger at SOD and also to scream about LE and lab sloppiness (they can't be trusted, they make mistakes...blah, blah, blah).
Articles on the risk of Touch DNA contamination:
http://www.ingentaconnect.com/content/iuatld/ijtld/1998/00000002/00000005/art00012
http://columbiauniversity.us/cu/biology/faculty-data/martin-chalfie/resources/nature-2002.pdf
RK interview (he insists he didn't touch anything except with his stick on page 4):
http://www.docstoc.com/docs/4782210/Casey-Anthony--Roy-Kronk-Interview-Transcript-released-March-6