What you posted is one person's opinion of the sound of the Dream 90. He is no more an expert than you or I. He says that he thinks the Dream 90 sounds "somewhere in between a regular single coil and a P-90". No...it sounds like a P-90 because it is a P-90. There are lots of P-90s that have different sounds from each other, but they are still their own thing.
Yes, the Dream 90 sounds more like a single coil than the Mean 90 because it is designed to sound brighter with less midrange than the Mean 90. (A Pearly Gates also sounds more like a single coil than an Invader).
The size of the bobbin has very little to do with the sound of the pup. If it did, the SD Lil'59 would sound like a single coil pup. Not even close.
The main influence on the sound (comparing a single coil with a P-90) is that the single coil has the poles, as the magnets, within a single coil of wire, and the P-90 has nickel poles within a single coil of wire, and dual opposing flat bar magnets. (Of course, a humbucker, even the Lil'59, has steel poles between the two coils, and one flat bar magnet beneath the poles).
Like I said, and as you can see in the pics you posted, the Dream has one coil with the poles inside that coil, and two flat bar mags. If the Dream were just the same but the bobbins were wider, it would sound exactly the same.