Zim needs to monitor and regulate where necessary internet usage. Those that blocked ITU are themselves leaders in internet regulation and monitoring through the tech like DPI, fibre slicing etc.
In US, NSA has unlimited access to all big companies like google, lbm, microsoft, at&t, go daddy etc which they pull strings from behind the scenes on behave of government directives.
Thus the same in UK, they have access to all major service providers which play tune to government.
for experiment, how about opening a .com or .co.uk website and start to post anything which can be deemed sensitive and see how long your website will stay online