Don't know about case closed (is it ever?)..
But everything Air France has said (more than one might expect TBH), tends to point towards that very interpretation.
Well, a simple reproduction of the ATA 34 under 11/15 (or whatever describes the related warning) confirming that ALL pitot tubes were disagreeing would end all speculation going on here.
Pitot Probe 1, then 2 and at last 3 being clogged or whatever other order of facts, provided that this message really applies to at least two getting 'out of service", would clearly explain almost everything that went on later.