Every consumer OS has such restrictions written in their agreement, and so do apps.
For example, the iTunes software license says this:
"You also agree that you will not use these products for any purposes prohibited by United States law, including, without limitation, the development, design, manufacture or production of nuclear, missiles, or chemical or biological weapons."
Yeah right. Like you can use iTunes to make a nuke. Or if someone were, that they'd stop because of the license.
