Medium format & anti-aliassing filters?

In another thread a link was included to a couple of Leica S2 37 plus MP images. Along with the images a poster had claimed that Canon or Nikon could never match medium format for quality because of the anti-aliassing filter fitted to the smaller format cameras. The post claimed that medium format digital cameras don't use these, so don't suffer the softening effects.

Any truth in any of that? Sounds like nonsense, but then what do I know. Certainly the in-focus* detail in the two S2 samples was amazing and I know the filter softens the image, but why would the anti-aliassing filter be essential for our cameras but not medium format?

* The photographer had used f/9.5 on a 180mm lens and the DoF was nowhere near enough. The eye was sharp, but the tips of the eyelashes, nose and opposite cheek were all OOF. Very silly when it was so easy to reshoot using more DoF.

I think if the person is more concerned with the AA filter than the fact that the sensor covers like 4x more real-estate then he's at least a bit delusional. Ultimately what makes Medium Format and Large Format more incredible than 135 is the bigger film/sensor, paired with glass designed to cover those larger film/sensors.

Secondly, I think that the AA filters today aren't creating such a difference as they were back in the 6mp and 8mp days, the pixel-pitch today is so tiny that I believe it renders the AA filter less and less necessary. AA filters work to smooth out the jaggies caused by pixels being too large. The sensor of the 7D for example at 18mp is about 50% the size of the one of a 10mp camera, and 40-45% the size of an 8mp camera. Smaller pixels = less jaggies guaranteed... = less need or work for the AA filter.

Then why does the 40D have a stronger AA filter than a much less dense 5D ?

I see they have used the Kodak KAF-37.5MP 45 x 30mm CCD sensor. Though again, why that should make any difference.