I really dislike your framing of chemistry enthusiasts as potential criminals. All the prohibition around chemicals makes it real hard to do fun stuff. Especially for people who don't want to break the law. Dangerous criminals don't care and will always find a way.
I wouldn't call it stockpiling if people keep small amounts of stuff around which they intent to use for (legal) experiments. It's not like he has tons of that stuff.
The real danger comes from farmers. Ammonium Nitrate (fertilizer) and diesel (tractors). They must be up to something [/s]