No one is word fucking anything.
"Chariots have a fixed armor save, as detailed in their army list entry. Such an armour save takes into account the hardiness of the of the chariot, the armour worn by the crew and any barding on the mounts (but barding still slows the model down)." p86.
So you don't sit there figuring out the various components of a chariot's save -- it's already done for you. If you look in the Empire army book, the armor save for the war altar is fixed at a 5+ (unless they've updated it in the FAQ - I haven't run one in awhile). Normally a chariot's armor save applies to the chariot as a whole and includes the crew (you never put wounds on the crew, you put them on the chariot). However, when you put a character on a chariot, it becomes a Ridden Monster, so the chariot as a whole has it's save and the character has his own save based on his armor (though he does get a +1 bonus for being on a Ridden Monster p.82).
So, the war altar gets it's 5+ armor save and a ward save of 4+ and the Arch Lector gets an armor save of however you kit him out and an additional +1 for being on the war altar -- and he also gets the 4+ ward save.
What probably muddles things is that most chariots carrying a character still have a crew that is considered part of the chariot, but not so the war altar -- it just has the Arch Lector (I wonder if this will change in our new book?) -- and he doesn't count as crew -- and it continues fighting even if he is killed, motivated by the will of Sigmar, no doubt.
