I think the 33 Phase 3 was the first AR to have galvanised panels. Only the main floor and chassis ones (the most rust-prone panel is the back panel
and that is not galvanised).
The 155 had more galvanising in more areas but still some bits are not galvanised. I don't think any car is completely galvanised as that'd be rather pointless (some panels never get attacked by salt/damp).
There have been major improvements in the quality of steel that last 40 years, that Chandler seems to be unaware of. Increased carbon-content makes steel far more oxidation resistant. Also paints, coatings and mastic sealing compunds are all more durable than in the stone age (presumably the last time Chandler updated his opinions).
Construction techniques have also moved on.. less hollow cavities and those that exist are filled with a foam material, to keep moisture out, etc.
The "rusty Italian car" saga came about due to the use of cheap imported steel from Russia, that was part of a deal between Fiat and the Soviet government that saw the transplant of Fiat 124/5 production to Russia - i.e. Lada Model No. 1, 2 (a 124 estate) and 4 and 5. Best of the lot is the 1.5 TC Model No. 6,
universally beloved of Moscow taxi-drivers, but I'm digressing...
The Russian steel was not as oxidation resistant as German steel, due to how it was processed. The problems particularly affected Fiat and Lancia cars made in the early to mid '70's.
By the time of the Uno and Tipo (early 80's) the problems had been resolved and the two brands were no more or less rusty than anything else on the market.
In fact the Tipo was the first mainstream manufacturer car to offer extensive galvanising in a vain attempt to knock the "rusty Fiat" legacy on the head once and for all. Didn't work, as Neaderthal man is alive and well, and living in Chandler's house... but how many rusty Tipo's do you see? Check out eBay for them.. beat up and abused.. but not rusty.
Alfa never used Russian steel and so any rust problems are mainly due to "poor" (by modern standards) construction methods and finish. Alfa's rust problems were pretty much par for the course for the 70's and even 80's. Certainly they were no worse than British, French or Japanese manufactured cars.
Dunno what he considers a paragon of rust-proof from the period... Hillman Avenger? Austin Princess? Ford Cortina? Talbot Horizon? Renault 5? Datsun 120? Even Jag E-Types are "rust-buckets" by what we're used to now.
Back then it was reckoned that 3 years was the period that it took for a new car to rust (note the due date of your car's first MOT) and life-expectancy was just 6 years.
Chandler and his ilk might make glib comments about Italian cars (dunno why he bothers to drive one, to be honest) but he's just showing himself up to be not only a bigot, but an ignorant one at that.