I'd just toss in this caution in looking at the various post-event pictures of the fuselage hole.
All those flaps of aluminum spent a long time after the event flapping in a 250-knot breeze until the plane landed. The post-landing shapes and extent of twisting or dislodgment may be quite a bit different in the pictures than they were at the actual moment of the "event" or immediately thereafter.
Tears may have grown larger - pieces that were originally bowed "out" or "in" may have bent back the other way over time in the airstream, depending on a host of factors that we can't even guess at given the disrupted airflow in the area (remaining shards of the fairing, the torn metal itself).
I do agree that the piece of beige cloth showing "ST(A?) below the "parcels" is likely one of the hold wall curtains - not necessarily "STA 700" because other curtains are similarly labeled with station numbers, but it is a probable suspect.
There is also CLEARLY no sign whatever of combustion or heat effects on the plasticky red and black wrapping materials plugging the hole, which would be present if this were a chemical blast. Those dacron/nylon/polyethylene-type materials are very sensitive to heat and fire and would quickly show discoloration and charring if there had been any kind of flame/blast, whether or not accelerated with O2.
Which does not rule out an O2 tank (or piping segment) as a physical cause - either as a source of gas pressure, perhaps violent, or as a source of metal wearing on the aircraft structure.
An aside - as a journalist I share everyone else's dismay (disgust?) with the sensational and sloppy reporting accompanying this incident (and other aviation incidents). Even on a smaller scale I am constantly having to explain to colleagues that, e.g. an airplane "stalling" does not mean the engine quit - etc. etc. I'm considering writing a "Reporter's Guide to Aviation" for the staffers at my newspaper - but it will always be an uphill battle, I'm afraid.