If you get the gist in his posts, he's commenting about the maturity and precision of the mouse interface for daily activities. In general, alternate UI does not and has not offered any clear advantage yet. Even MT UI has not delivered where mouse UI is prevalent. In general, MT UI will have the problems I mentioned. Perhaps that's partly why MS experimented with a pen-based input concept like Courier.
Unlike your hasty jump to conclusion, this does not imply that MT interfaces does not offer any advantage over mouse. It may mean that they can be used in areas not to replace mouse, but to complement it or co-exist with it. e.g., Mouse is not used on truly mobile platforms such as phones and pads where there is no desk around. Or MT interface may overcome its shortcomings somehow to compete better with mouse.
Similarly, from what he has seen so far, he feels that motion sensing hasn't offered a clear advantage to sticks. Whether and how motion controller can replace stick is an on-going work (See Socom 4 and so many Wii examples). In fact, the scope should be natural interface instead of just motion sensing.