I'll say why: Oro had his body sealed by itachi. Although his body was sealed, his chakra still remains in ank, suppressed though. My theory is that oro cannot archive physical transformation without the Yin chakra that was sealed by itachi. In order to achieve physical transformation, he will have to surpass ankos chakra and take her body to achieve a physical transformation. He has to use ankos Yin chakra, thus he might still be weakened just like how kurama is now.
The most logical way for sasuke to meet oro would either be using his sharingan to get to him just like he did with naruto and kurama, or push anko past her limit like itachi did to sasuke, so that ankos chairs would most likely be low enough to were oro can suppress her.
Sasuke most likely will use his sharingan though, to save time and conserve chakra by not fighting oro.
What do you guys think about this theory? Its pretty logical don't you think?

The most logical way for sasuke to meet oro would either be using his sharingan to get to him just like he did with naruto and kurama, or push anko past her limit like itachi did to sasuke, so that ankos chairs would most likely be low enough to were oro can suppress her.
Sasuke most likely will use his sharingan though, to save time and conserve chakra by not fighting oro.
What do you guys think about this theory? Its pretty logical don't you think?