This article ignores the context behind the proposal. Many companies, schools, and prisons are MITMing all SSL traffic today for a variety of liability reasons. Today those users get no notice that their Web browsing is being observed and censored. Trusted proxies are intended to give those users some notice that they're being MITMed.
I agree that MITM proxies shouldn't be used on the public Internet and thus we shouldn't make it easier to do so, but what about the people who are already being MITMed? Is there another way to solve this problem or must we throw corporate Web users under the bus to save the public?