Because that sure didn’t seem like a ‘redeemed’ Anakin.

I thought it did. The world between worlds is tied to the cosmic force, so "force ghost" anakin could probably appear however he wanted, so sith eyes and red saber were used because thats what Ahsoka was aftaid of, and confronting fears is very Jedi - Yoda went through a similar experience fighting a manifestation of the dark side within him. Additionally, Ahsoka's fear was also impacting what we saw on screen - I don't think he was choosing to flash into Vader, I think that was Ahsoka projecting.