Here is one of the few other singing/dancing games I can find that 1up reviewed at all. As you can see, they hated it -- they hated it a lot more than anyone else, in fact. And it's not for the Wii. For most games in this genre (Singstar and DDR being the two most obvious franchises) 1up doesn't even take the time to review them at all. There isn't a single 1up review for any Singstar game that I can see, although I'm sure I'm missing at least one buried in there.
I think, if anything, this shows that they simply hate this genre of games, not that they're specifically biased against Nintendo.
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