First, remember the Breaking News Consumer's Handbook: Airline Edition ( https://media2.wnyc.org/i/620/620/l/80/1/BNCHAE.jpg ). Second, I'm sure that Mr. Robin is a nice guy, but there's no need to publish his stray speculations just two days after the crash.
The most plausible interpretation is that the co-pilot through a voluntary act had refused to open the cabin door to let the captain in. He pushed the button to trigger the aircraft to lose altitude. He operated this button for a reason we don't know yet, but it appears that the reason was to destroy this plane.