This isn't true. There have only been two weeks when Wii outsold Vita, hardware-wise.
I think they were just pointing out the fact that the wii actually managed to outsell it once, and that little box has absolutely nothing to offer anymore in Japan.
Though yeah, it did seem kinda pointless to make that point. Biggest problem is that the PSP is constantly outselling it.
Edit: Actually, I think the week the wii outsold the PSV was when MP9 came it out, so it did have something.