No one is arguing anything that you are saying, CAIR is not to be trusted that is certain. However, based on your email, you seem to be believing that CAIR is representing that the data on this cardboard is accurate. That is not what I am seeing or reading. They are pointing to the mockery that this soldier is 'allegedly' making of these boys and pointing to atrocities that US military might be accused of.
If this soldier did this, he needs to be reprimanded, if it is a photo touch up obviously not.
If the soldier is reprimanded, his argument might be that he was pointing to the 'irony' that US Soldiers are being accused of when in actuality the truth is that (as you say) this young man would not be smiling if it is true.