Camera shake is somewhat reduced by image stabilization/vibration reduction technology in many of the lenses available today. Or, shoot at a faster shutter speed - typically 1/<focal length> - to remove camera shake issues from the photograph. But neither stabilization, 1/<FL> shutter speed, or even a tripod will prevent subject blurring due to moving faster than the shutter speed used. I could take pictures of racecars using 1/200th of a second mounted on a tripod and most of them will come out blurred.
As far as more 'tightly packed' pixels reducing camera shake? That's a new one on me. As mentioned above, the smaller, tighter pixels of a crop sensor vs a full frame sensor will typically have more noise, and, if viewed at high magnification, may not result an image as sharp as the same lens on a FF camera would produce. The increased noise effectively reduces the defining 'edges' of subjects & items in a photograph, making it appear less sharp. But more often, degree of sharpness is affected more by accurate focus and overall lens quality ($$), and the photographer, than the camera body in ones' hand.