Anakin's robes are different yes, but only in material colors. The cut of his robes in AOTC is a standard Jedi design, if you have the visual dictionary for AOTC. You'll find that Shaak Ti has some very dark colors and a completely different style of Robe. Hell Barriss Offee has completely black robes! The debate will continue until a decision is made. But I don't think that Anakin should be accepted to the 501st, he is welcome in the Rebel Legion.