Reading about this yesterday the basis seems to be chatter that terrorists were developing a bomb that could be contained within a battery and masked from traditional screening.
The logic behind such a ban would be that such a device had to be manually triggered, but I'm pretty sure plane bombers mastered pressure switches in the '80s when lots of planes blew up prior to any baggage screening occuring.
The large flaw with banning devices on only a few airlines is that it then increases the risk for everybody else in much the same way only having a small % of the population vaccinated doesn't make the world safe for everybody. With the huge debates in the US over ME3 carriers in recent years it does seem a little coincidental.