You say that like it's a bad thing. All Alpha Legion information should be cast in doubt. That's a cornerstone of the entire legion. Everything about them is layered over itself, with small bits of truth sprinkled throughout the rumors.
What the FW HH write-up makes abundantly clear is that there's two major sides to the Alpha Legion. The side who stays hidden and disguises themselves as others, performing more covert operations, but just as large is the side that makes themselves extremely visible, with bright colors, heraldry and large formations, to act as the face of the legion. This is not anything that was previously known.