$rm SO(10)$ grand unified model restores the parity symmetry lost in $rm SU(5)$ model

It is said in Lie Algebras in Particle Physics 2ed – From Isospin to Unified Theories (Georgi, 1999) p.285, Georgi said that

$rm SO(10)$ grand unified model restores the parity symmetry that was lost completely in $rm SU(5)$ model.

However, it seems to me that the spinor representation 16 alone in $rm SO(10)$ model breaks the parity symmetry. Can experts clarify the conflict?

It is possible that the parity here means something not just $P$ but mixed with other internal symmetries such as automorphisms (inner or outer?) of the gauge group. What exactly does Gerogi mean?