They removed it because there was a glitch that one could use to escape the Creative Island while still keeping flying and weapon spawning creative features. This allowed among other things, copying things betwee 2 separately loaded Creative islands. Many creators used this to set up islands with hacked on weapons not normally found in Creative mode and then share them with others so that others could copy the hacked in weapons to their own Creative islands.
While loading up different creative islands in different portals is no longer a thing, as is the ability to leave boundaries of your creative island in any way, they still would probably want to patch any exploitable glitches out of the Brute before they bring it back.
As they have been working to add new content more than fix old bugs, I doubt we will see the Brute get brought back any time soon. Most likely it will at earliest be brought back for Season X in OG mode. When they do this, they will paych the bugs and that should make it be allowed for use in Creative mode.