Because it spends more time where the flow is higher.
I never pick lift just because the lift flattens out or backs up a bit. Jones disagrees with me, but he is wrong.
My guess is if the OP puts his head on a bench and put the intake on it, the flow numbers would drop but the flow curve would change and it wouldn't lay down like that at higher lifts.
And even if it does lay down, use lift.
BTW, I seriously doubt any head pulls 28 inches at max lift. In fact, I've seen CFD stuff that says it's nowhere close.
That means if you reduce the test pressure to say 10 inches and test again you won't see that port lay down.
I always test at 28 for a base line, then go as high as the bench will go, and then drop down to 10 or so and then start looking at what to do.