This is troublesome for us as well, as we are unable to use device access policies for any iOS9 devices. It seems that this is certainly something that Ruckus can fix as iOS devices do send OS fingerprinting info using DHCP Option 55 parameters 1,121,3,6,15,119,252. From this Ruckus KB it appears that Ruckus supports DHCP Option 55 for client fingerprinting.
https://support.ruckuswireless.com/answers/000001668I've seen that other competing products are able to ID iOS9 devices using DHCP Option 55; it just seems like the proper parameters have to be added for the recognition to occur.