You said it best when you said you don't understand. If you can't define what material support mean in its fullest geometry then why would you feel safe accepting it as in your best interests.
"We are disappointed that the Supreme Court has upheld a law that inhibits the work of human rights and conflict resolution groups. The 'material support law' – which is aimed at putting an end to terrorism – actually threatens our work and the work of many other peacemaking organizations that must interact directly with groups that have engaged in violence. The vague language of the law leaves us wondering if we will be prosecuted for our work to promote peace and freedom." Jimmy Carter
Not only are you now expressly forbidden freedom of speech, thought and association. You will be considered an enemy of the state and immediately you lose any and all rights to a free trial as a result.
Define clearly how material support can never be bent to the best interests of the government?