I don't know if this device works, but this is just wrong: >"I'm sorry to say, but the Brussels attack, this would have instantly sorted out the terrorists before they came into the terminal, and similarly the concert in Paris," he says. "If it had been on the doors there, it would have stopped people getting in." The terrorists who attacked the Bataclan didn't arrive as simple concert goers, they had AK-47s and shot…
That, of course, ignores a central lesson of the Brussels attacks: They happened before security. This device might make it reasonably hard to get explosives into an airport building and concerts halls (because thousands theatres like the Bataclan are totally going to invest millions in these devices and the necessary physical reconstruction), but there are plenty of other buildings where large numbers of people congregate, including busy streets that will be impossible to protect like this.
Also, having a mechanism to seal your targets inside during an attack is totally never going to be abused by the bad guys (and if you evacuate on a trigger, you just need a few guys with AKs outside the exits).
That said, I'm sure there are good applications for an effective non-intrusive explosives detector (eg in making airport security smoother) -- these attacks just ain't it.