How do you find the centripetal acceleration of any point on a body performing both rotational and translational motion.
For example, in pure rolling if we find centripetal acceleration of the topmost point about the IAOR, it will be $\omega ^{2}2r$ but when you find it about the COM it will be $\omega ^{2}r$
But here to find the normal force we do consider centrifugal force of the COM about the IAOR. $$mg\sin \theta + T\cos \theta - m\omega ^{2}r = N $$