The iOS update packages must come from a range of webservers and if you could find those specific addresses and mask them into a deny policy and test...it might just work. But almost certainly going to be unexpected gotchas such as other app updates being blocked.
Haven't tried it so cannot give definitive.
Ruckus will give you basic traffic throttling but not much more unless you can find some really creative way to achieve what you are asking.That's filter/firewall/traffic management stuff.
============= Just googled ios update servers...
Software Update must communicate with Apple's update servers in order to download and install updates. Ask your network administrator to allow the following server addresses on your DNS and proxy servers.
Hmm? Maybe blocking swscan.apple.com might be enough.