The utterly marginal status of Standard Arabic in conversation within this group (and elsewhere in Algeria) contrasts sharply with that of French. 22% of the sample claimed to address Kabyle strangers in French, and 26% to speak it with their friends. More tellingly, 38% chose it as the language they spoke in at work, and no less than 68% for speaking about science. It's interesting to find an official language that doesn't dominate even in contexts like that! In short, while Standard Arabic is taboo for conversation, French is not. There are of course circumstances where it could be inappropriate, but there is no blanket ban as with Standard Arabic.
What does this imply for language policy? I'm no policy analyst, but here are my thoughts...
As far as the linguistic majority goes, only a spoken language can hope to displace French from the spoken domain, and long-standing efforts to break the taboo on speaking Standard Arabic have been utterly futile. Maybe it's time for those who want Arabic to be official in practice and not just in theory to acknowledge and support the existing complementary distribution of functions between Standard and Algerian Arabic, rather than treating the latter as some kind of unfortunate necessity. Demanding that officials consistently speak to the public in Standard Arabic instead of French is not always realistic, but demanding that they speak in a high register of Algerian Arabic could be. But that will only happen if people learn to value the language they speak, rather than dismissing it.
For the minority, it suggests that the main threat to Berber comes not from school, but rather from daily life in non-Berber-speaking environments. If so, solutions should focus less on making sure that Berbers can study Berber at school (though that is certainly desirable for other reasons), and more on getting non-Berbers in linguistically mixed contexts to study Berber and use it in conversation - almost the opposite of existing policy.