Okay, that makes a lot of sense. Absorbing it rapidly would then spike blood sugar, and that sort of thing done too often for too long leads to things like type 2 diabetes as you build up insulin resistance. So that does show how the sugar in milk would be less harmful than the same amount of sugar added to a plant-based milk substitute.
Fat isn’t exactly the bad guy that it was cracked up to be a while back. I think a lot of these things are driven by industry lobbies who want to drive business their own way.
To possibly clarify, lactose, the sugar in milk, is what is known as a disaccharide (complex sugar) because it is composed of two monosaccharides (simple sugars), glucose and galactose, bonded together. The lactase enzyme is required to hydrolyze (digest) lactose, which is not absorbable in the intestines, into the simple sugars that are.
The result is unusual, as your link notes.
The glycemic index of lactose has been determined and is reported as 46, which classifies it as a low-GI carbohydrate. Interestingly, the monosaccharides of lactose, galactose and glucose have reported GI values of 23 and 100, respectively [3], so the value of lactose is lower than what would be expected based on its constituent monosaccharides. …
While lactose alone is, thus, already classified as a low-GI carbohydrate, GI values of dairy products are even lower than what would be expected purely based on lactose content.
Context is everything, even in the intestines.
You are correct that I should have spelled that out. Thanks for the help.
I actually don’t get it though?
Yes lactose needs to be enzymatically hydrolyzed in the small intestine to be absorbed, which is a step. But so does sucrose (the disaccharide that is table sugar), and I don’t think sucrase is any slower than lactase at the job. I am skeptical that that is actually a major factor.
But it is a fairly low glycemic index carbohydrate.
My WAG is that adult lactase persistence is a relative thing. I speculate that even lactose tolerant adults don’t fully hydrolyze all the lactose they ingest. Some gets to the bacteria which help out too, just not to a level that causes discomfort.
It appears to be true that lactose tolerant types don’t hydrolyze all the lactose intake but the amount is small and hasn’t been studied well. All the cites seem to go back to Bond and Levitt, from 1976, when lactose tolerant individuals could be classified as “normals.” (Levitt is the Grand Old Man of LI. Full disclosure: I corresponded with him when writing my book. He did not like amateurs treading on his turf, but he had to concede that I addressed all his concerns. My best moment came when he said You Have to Mention This and I responded that I put it into the first chapter.)
All of four (4) normals were studied, whose undigested lactose ranged from 0-8%. Unless one is trying the gallon of milk in an hour challenge, the amount of undigested lactose in normal usage by those who are tolerant is very low.
I have a calculator, and I have bad news for you.
Thanks for that information!
So in vivo I guess lactase IS slower than sucrase?
Don’t know a thing about scrase.
I’m a generalist whose specialties are exceedingly narrow. 
Naw, I use a very tiny glass for my milk—1-milliliter to be precise—so, I’m well below that million somatic cell count.