Some people in the comments were wishing we could boil down David’s excellent analysis into a pithy statement, and in the comments of a later post one guy got the point backwards, so let me repeat here what I said to clarify. The point David made was (in my words)
(1) just because workers might be better off by choosing to work less under ObamaCare than by continuing to work the same amount under ObamaCare,
(2) doesn’t mean that they are better off under ObamaCare than without it.
That’s a very obvious point, but it requires you to think of three things at once. The people saying the ACA “obviously” benefits the workers who are choosing to reduce work hours are only looking at the two things contained in point (1).