No, there isn't. Most of the emulators for the previous gen consoles (I consider the Wii to have previous gen hardware, lol) do not have 2xSaI texture scaling for a number of reasons, of which I assume are:
1) texture size. In the last 2 gens, it was about 16-128 px while in PS2 it can reach up to 256 px and 512 px (perhaps more) for the Wii. To make the emulator upscale all of the textures on the fly will bring the computer to its knees. (IMHO, since I don't have proper metrics for these)
2) the scaling algorithms are more useful for pixels that have lots of flat, vibrant colours. Thus they produce more noticible results in older games as compared to the textures of nowadays that have a lot of gradients and minute details. Even from the modified texture I posted in the example above, you can see that although the sprite is less blurry, there is still some distortion where the pixel edge were, as seen at the sword for example.
If you're looking into a full-screen filter (as in the shader settings), I'm not sure which would produce the best result. Perhaps a 'sharpen' filter would be good, but it's not there in the shader list so you'd have have to program one yourself.
I'd rather live with the blurriness and sit a bit further from the monitor than play with effed-up sprites.