Well yeah, the shit is stupid. He could smoke weed if he wanted to since the NFL only tests for weed for a very specific window (I think it's during three of four weeks of training camp and that's it!). They don't test for weed the rest of the season.
Chris Carter was very specific too lol, he said he smoked weed laced with PCP and the synthetic weed story just sounds better. I think he's probably right knowing that NFL players can and do smoke weed during the season without having to worry one bit.