And because nowhere in the constitution does it say that conviction of a felony means you lose you right to bear arms, the day you are released from prison you are given your guns back, preferably cleaned and well oiled and ready for use.
Nowhere in the Constitution does it say that child pornography is NOT protected by the 1st Amendment either.
Perhaps you fail to understand the purpose of the Constitution. It isn't a laundry list of do's and don'ts for the people. It is an enumeration of permissions for the government, a definition of the government, if you will. Further, "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people" Thus, banning child pornography is, and should be, controlled by the States. This means, simply, that the federal government cannot expand its control without permission of the states, or the people. Of course, we have violated this hundreds of time, all in the name of "the general welfare".
We have committed numerous sins in the name of "the general welfare" clause. James Madison, one of the collaborators who developed the Constitution would tell you that if it ain't in the Constitution, you can do whatever you wish. Alexander Hamilton, on the other hand, believes that the "general welfare" clause allows the government to do whatever they wish - as long as they cloak it in promoting the general welfare.
Such is the Constitutional argument that continues until today.