Sprogget
You have the option of driving your car with flat tyres, or no with oil or water in the engine. You could even turn off the warning lights by pulling the fuses. But only an idiot would do it
Disabling updates, and blacklisting IE9 is a similar kind of act, unless you have a very specific reason for doing so: and very few do have a valid reason. IE9 is much more secure, is quicker, and the availability of future updates requires its presence.
If you want to know what I regard as a "specific reason" for not installing it, I'd have to suggest the UK Dept of Work and Pensions, some of whose databases have not been rewritten to be compatible with anything newer than IE6. Thats a very specific reason - though in my view it not really a valid reason, its just poor management.