This guy is a public relations executive working for the pharmaceutical company which developed this drug.
It has not been tested to protect humans from radiation.
What says stem cells are involved? The pharma's website doesn't mention this.
The drug is meant to be administered prior to exposure. I don't see that being more effective or expedient than evacuation for the civilian population. Sounds like something naval propulsion commands or accident response teams should stock for emergencies, not FEMA.