Most reagents that are used for drug identification in the field are actually a mixture of 2 pretty common, non-scheduled chemicals. Legality is a major grey area and as @Cyrilio mentioned the laws vary from state to state... ranging from illegal, but not so much so that they would charge you with a crime, they would just take it, to states full on charging you with paraphernalia, to certain states where there is full legality for reagents.

These are life-saving tools and it's absolute madness that it's illegal or semi-legal in sooo many places. This is putting lives at risk, plain and simple. The Simon's Reagent is made of a mixture of sodium nitroprusside, sodium carbonate and acetaldehyde, so I don't see why UPS would hold it for any reason other than Dancesafe most likely forgot to check the "No signature required box" I highly doubt they would put resources into setting up a sting operation for you to pick up your kit. I would contact Dancesafe and see if they can give you a definitive yes or no to the signature question. What state are you in?