You're right, that's no possible moving, but there is exceptions. I'd read the link that you dropped here, and takes me to this c4d's tip in the article:
In the abc object, goes to the alembic tab, and enable the option Update PSR, when is enabled is possible to change the scale, rotation, and position very slightly, because depends on how os animated your abc file. For example:
I animated a cube rotating in your own axis, so I did a abc from them.
I imported the abc to new project, and enabled the Update PSR, to change the scale and position. Worked fine!
But if I try to change the rotation, it start to bug, and create conflict with the original rotation that was animated.
So, I just can make changes using Update PSR in no animated parameters.
Ok, it's no enough, but is some thing.
Actually, is my first workflow that I've got with abc file, I hope to learning more to work better with those files later!