This will be usable for a few years, then you'll eventually have some plausible deniablity when it it over used
I also know from experience that a 50ml pot of SmartWater is enough to chemically mark every PC or electrical item in a school several times a year and last several years.
It's also very good for equipment recovery. It basically guarantees identification / return of stolen property if it comes into police hands. but with SmartWater once it's in police possession even the smallest tiny speck of SmartWater (which can be deployed even on hard-to-cleanse areas like across the PCB's of (unpowered) motherboards) or similar will link it to it's owner.
If this stuff spreads with the ease that TFA describes, it's going to get everywhere. How many law enforcement agencies do you think are going to take Joe Blow's word that they "only touched something that was touched by someone else, who I shook hands with?
Experiment: Spill some powered detergent with color safe bleach. Leave it in a public space for a day. Use a UV light to track its spread. Count how many people are now "marked" that were not the original spilling "criminal".
Yes, this product is uniquely identified, and easily indiscriminately spread. Just use Monsanto as an example of a unique item is being spread by the wind to people being accused of stealing.