Earlier quoted context omitted.
No one is saying it isn't against federal law. It's still a demented justification to turn someone away from the country. "You can come here, buy weed in a majority of states, and face no fear of repercussions... Until you try and come back in". That's nutty . It's batshit. And, the real reason he was brought in - as brought up by the Immi officers - was that he was doing journalism at one of the anti-genocide protes…
It's probably not a good idea to have people on visas attending protests. Keep in mind I'm very much not pro Isreal, but it's not practical or moral to have foreign partisans participating in our politics that way.
That would be called 'freedom of assembly', which is a universal human right (see Article 20 of the UNDHR). Highly moral, most practical, and widely recognized as such.