On the one hand, you don't expect to make important choices about future use of your computer during a Windows Update operation.
On the other hand, if it looks like a piece of malware offering to give you new free software, evidence is that very many people will embrace it enthusiastically. The Internet is giving me free things! Hooray!
But next time they try to web browse, they may not enjoy !the experience. Why does Control Shift R not work any more!
Example: around when the British Gas (heating) monopoly was broken up, I got a letter saying I'd chosen to switch to let's say the Bolivian Marching Powder & Domestic Fuel Company, which I hadn't. Dopey British Gas sent me that letter right at the end of a four week change-your-mind period and so I couldn't say no. Apparently I had to wait a year before they could reverse it and recognise the real contract, and also put my Member of Parliament onto them. I didn't get a bill from the Bolivian Marching Powder Company and I ended up paying for a year's fuel in a hurry later. But what if British Gas was responsible for the entire experience? They had me as customer for a year when I couldn't choose to switch to a real gas supplier. Maybe two years if they legally got to keep me for that long afterwards.
Arrange for the customer to have a bad experience with your competitor (if you can), and they'll be glad to stay with you.