I could be wrong about this, but to me, it is simple. When the Anthonys made their statements, they were merely stating what they believed at that time. To my knowledge, they have been cleared as to having anything to do with Caylee's disappearance. Cindy's statements were inconsistent, but I don't believe they were outright lies... just what she had been told by her lying daughter. What they have said to the media since then, cannot be classified as lies, they were not under oath. That can't be prosecuted as obstruction of justice.
If Cindy washed those pants, knowing that they could be evidence, that's different, however she DID call LE to come pick them up... so by doing that, they gave her a pass. Every spokesperson for LE that I have heard so far has stated the Anthonys are not under suspicion for anything. They have said that they cooperated fully. Does not sound to me like they intend to charge them with obstruction or lying under oath.
Like I said, this is just my opinion, and I could be wrong. But LE knows that they are under tremendous pressure, and hurting right now because of Caylee being missing. They know it is next to impossible for them to accept that Caylee is probably dead. I don't believe they would be callous enough to charge them with anything under those circumstances.
I know that many will disagree with me, and that's okay. But none of us really know how we would react if we had to face the same situation, do we? And also... think about this... most of us claim to love Caylee and want her to be found. Yet we never knew her at all... these grandparents were with her every day until June-whatever... she was their pride and joy. Think about how much harder this is on them than it is us. We can only imagine how sweet and precious she is.... they lived it!!!!