I disagree with the author that this is middle class. A two bedroom apartment is the very definition of impoverished lower class loser, just above homeless.
Middle class means a detached 3 bedroom in the suburbs, with biweekly maid service, two financed cars, health care to the point you don't need to worry about it at all, and buying whatever you want at the supermarket.
What middle class does not include is any one of: a mansion, live in staff, a yacht, full time nannies instead of occasional baby sitters, swiss boarding school for the children, a groomsman for the horse, a pool boy, a cabana, a private plane, or zero income tax.
This is what skilled factory workers and teachers had in the 1960s, 1970s, and 1980s. Above them, designers, engineers and lawyers, comprised the upper class, or upper middle class.