Then again, I'll probably never understand what the pilots of AF447 were thinking, and their actions lacked coherence. But I would expect a perceptive pilot to notice the change of law. Especially given the stall warning - normal law has full stall protection, so AFAIK hearing a stall warning is strongly indicative of non-normal law.

AFAIK pilots can always revert to direct law by disabling the primary computers on the overhead panel. The article is curious though, because it states the pilots tried to reenable the third primary computer after it failed, which resulted in a second dive. They gave up on restarting it after that, but left the other primary computers engaged, but were concerned about whether the plane would behave. My (potentially misguided) instinct there would be to throw out the primary computers altogether as a precaution.

It wouldn't surprise me if Airbus training encouraged pilots to always try to return to the maximum level of automation and envelope protection after a failure. In that context - the context of Airbus's culture - deliberately reverting to direct law could be seen as irresponsible, even if it seems like the opposite could be said to be the case in this incident. If so, it'd just be another way in which Airbus's approach to aviation raises questions...