Jamming something as powerful as Irbis is an issue with or without active array.
But:
1)AESA is more expensive.
2)Zhuk-AE is a weak installation for su-35-sized fighter. Enlsrgrment of the array is close to developing a new system, because cooling and processing, which is still more expensive.
Phazotron stated around ~10 years ago that they were planning to enlarge Zhuk-AE for Flanker installation. However I gather nothing has come out of it. And why would, Zhuk-A(E) is dead. Supposedly its performance in Indian MMRCA comparison wasn't too good. Zhuk-AM which they are developing for MiG-35 is quite different.