That particular argument doesn’t hold water. We don’t generally subscribe to this kind of argument.
The general principle behind the specific argument you bring up here is this: All expression which is likely to inspire someone toward illegal action should itself be illegal.
CP is likely to inspire some people toward child abuse. Child abuse is illegal. Thus the distribution of CP should be illegal.
We don’t do this anywhere else.
Yes we do. Plenty of stuff is banned by federal law. Snuff films, for the same reason as CP/CSAM. Obscene pornography (stuff showing abuse or degradation, even if it’s just acting) isn’t illegal to posses, but it is illegal to buy, distribute or carry across state lines. Ivory is illegal, unless you have a certificate proving it is from pre-1989. These are all banned to stop demand.
And that’s not even getting started Americas long history of banning books.