The source of the dissent is probably this:
I still do some flight instructing here and there. If one of my students turns out to be a member of one of these groups, am I going to jail or is there a "knowingly and willingly" requirement? Edit: Saw the "knowingly" clause. That seems reasonable.The court ruled 6-3 Monday that the government may prohibit all forms of aid to designated terrorist groups, even if the support consists of training and advice about entirely peaceful and legal activities.
Material support intended even for benign purposes can help a terrorist group in other ways, Chief Justice John Roberts said in his majority opinion.
I'm on the fence on this one. Offering advice on plumbing doesn't strike me as something that should be worthy of jail time. Then again, who offers advice on plumbing to Al-Qaida?