That nearly happened to me, except I stopped it before the update completed download. I supposed the "OK" button was not on the update? I don't remember correctly, but I thought the previous update did have "OK" button that you tap on to confirm with the install, but no way to deny it. Out of curiosity, does your setup have 2 routers, a router behind a router? If so, this could be the problem, as you may already read my previous post.
I setup my own proxy server and it seems to be blocking out the update so far, but I dunno how long this will work. However I used wildcard in the url for the proxy server to deny incoming and outgoing access. Also allows me to keep an eye on the connection activity and MK8 seems not to use much bandwidth. After about 1½ hours of playing MK8 online, bandwidth usage was only 241KB. Perhaps the server did not record all the activities going on but I thought this was on the low side.