it looks stronger than other filter canon have used together with theirs newer 18Mp cameras
And yet, it is neither too strong nor too weak
. To turn the argument around, all three of the other cameras in your sample shot have AA filters that are too WEAK. As a result, you experience moire. Moire is something we have no decent tools to correct in post. The tools we do have are tedious, and must be applied locally. A too-weak AA filter is worse than a just-right or too-strong filter, as when you have a just-right and too-strong filter, all it takes is a little global sharpening to correct in post. Nature is FULL of interfering patterns.
It is relatively rare to not have the need for an AA filter. The cases where you might be ok are most landscapes, or if you regularly shoot below the DLA (in which case, diffraction will soften enough to act as the AA filter itself.)
However even in nature, there are plenty of repeating or nearly repeating patterns. Birds feathers are an excellent example. Fur on wildlife. Striated detail in leaves or other natural materials that often show up in macro photography. There are also plenty of things that just experience aliasing, not necessarily moire, such as twigs in trees, power lines, strong edges on any surface or structure, etc. These are all things we have to correct in post if we don't have an AA filter or have an AA filter that is too weak.
I've never seen meaningful, visible softening in the 7D that was not due to a lens. When I use top-end telephoto glass, I see no softening whatsoever. That tells me that the bulk of "softness" people experience is due to the lens, or an incorrect AFMA setting. If you use high quality glass, softness just doesn't occur. It may not be hypersharp either, but it is still sharp as a tack every single time, and if I want things to be even sharper, I can always add just a little sharpening in post. Note, here, that the shot of the finch with the 500/4 L II + 1.4x TC was NOT sharpened. That sharpness is strait out of the camera.