Unfortunately by the time this detects a piece of ivory, the damage is already done. If it took 3 years to inject 20 rhinos, it's unlikely that a large enough portion of the population could be injected to act as an effective deterrent for those actually killing the animals. Even for those actually involved in moving the ivory, it's only a deterrent if they actually face consequences at these borders - many states have weak enforcement of anti-ivory laws, and many more have bribable customs agents. Further, ivory has a value to weight ratio that is extremely conducive to smuggling.