The former; it's a unifying step. For example, smallcraft and vehicles have lower armor values.
DonM's Consolidated CT Errata says otherwise:
"Page 41, Rule 75: Naval Vessels, B – Armor (correction): The Striker armor rating corresponds to High Guard armor factors according to the table below:
Armor Rating
High Guard 0 1 2 3 4 5 6 7 +1
Striker 40 44 47 50 52 54 56 57 +1"
So at least I am not the only person to see that it could be interpreted either way. (I was looking for the original Striker Errata, to check on something else but could't find my copy).