0.) We can't be locked out of the browser by nintendo without an update, and even if we were blocked out to some extent im pretty sure nobody would be affected due to tubehax dns.
1.) If you need reassurance then I don't think you should be modding because there is huge risks regardless of what you do.
2.) Try reading the sticked posts, that will answer a ton of your questions in this thread.
3.) It is illogical for nintendo to block the browser in its entirety, and blocking certain domains would require an update.
If you read the posts, you would know to block updates and this would not be a problem at all.
4.) If you are so worried about upgrading to 5.5.1, then just stay on 5.5.0. Not much of a difference really.
There, happy now? let us cease the pointless fighting.
Most "random users" have already used the exploit and can provided viable information to help you