He's making a point that he flies a dot high; fly the glideslope and you'll be in his wake. He may also land a little longer, just like anyone else does in a light airplane. It's a courtesy message to educate others that the large airplane ahead may very well be doing the same thing that many light airplane pilots do.
When I fly an approach in a Lear behind a heavy aircraft, I tend to fly a little high, too. I land a little long.
In a 747, I tend to fly with the needles centered and if I land long it's simply because I'm a poor pilot. BelArgUSA does it becuase he's avoiding wake turbulence. Regardless, his point is valid; stay heads up for wake. Don't assume that it's settled below if flying on the glideslope, and be aware that even large airplanes take measures to avoid wake...which might include landing past the touchdown point of the preceding aircraft, in some cases.