EDIT: Nope. Not true. I made a bad assumption and immortalized it in a bad post. Don’t listen to me, I know not what I’m talking about…
WTF?! So apparently, staff decided to automatically make author portraits visible when posting from a side blog - this is pretty dangerous for people who run side blogs that can’t or should not be associated with their main blog - I think of the “fandomhatesxxx” blogs or xkit-extension (xkitguy) or a lot of trans folks blogs and the like.
You can remove it by going to the settings page for your side blog(s) and clicking the slider next to Blog Avatar - Show author portraits. It’s enable by default because staff actively hates its users.