This is something I’d really like to have an option for: Whenever I transform a bitmap selection, it becomes fuzzy and distorted:
Technically this would be better described as interpolation than antialiasing. Currently we use a linear interpolation algorithm for scaling. There has been some talk about supporting nearest neighbour interpolation in the future which would be what you want for this use case. It could be a while before that actually makes it into the program however. Rotation is a different case which is probably more complex to implement and less useful, so I would be surprised if any new modes will be added for that ever.
For the time being, you can export your images, edit them in a dedicated image editor, and import them back in if you need this functionality right away. GIMP and Krita both can do this by setting the interpolation and filter respectively, and any other half-decent image editor will have similar options.