The concern with those is that the liquid can be used to make an explosive (acetone peroxide), but that is only explosive when dried out. Ironically, you can actually bring a large amount of one of the main ingredients on board (hydrogen peroxide) if you have a doctors note.
Something they don't seem concerned about is gun cotton. It looks, feels, and smells exactly like cotton, but goes boom. You might look suspicious bringing a bale of cotton in your carry-on, but you could treat jeans and t-shirts into it. Then, you have a bag packed full of explosives, that looks like clothes even under close examination.
I think they were more concerned about people smuggling drugs dissolved in water, terrorism is, as ever, a convenient excuse.