???Scenario's:
1. Shared computer, using the same Windows login/password => why worry about router access when you trust that person with all your documents and data?
This scenario there's more chance of messing up the Windows installation than the router setup I guess...
2. Shared computer, different accounts => the cache is not shared in this scenario, so the router should not give access. If it does (?) you have a faulty Windows setup.
I guess this would not be a high score on the feature wish list...