The text posted is an excerpt. The original, available at the link, makes the distinction between what the "fundamentalists" say and "what their own theological forebears, the Protestant Reformers, had to say".
The article elaborates:
The Nestorian claim that Mary did not give birth to the unified person of Jesus Christ attempts to separate Christ’s human nature from his divine nature, creating two separate and distinct persons—one divine and one human—united in a loose affiliation. It is therefore a Christological heresy, which even the Protestant Reformers recognized. Both Martin Luther and John Calvin insisted on Mary’s divine maternity.
As you can see, no confusion exists: the author distinguishes between "fundamentalists" and "their own theological forebears" Luther and Calvin.
to say that "Protestant Reformers often assert that Mary...only carried Christ’s human nature" is both laughable and libel
For example, at post 3 Angry Write Mail says "Mary was the mother of the MAN Jesus"; how is that different from what you quote and call libel?
Sure, there are the occasional fringe groups - there are always exceptions. And I'm not even sure AWM's usage should be read in the way many are reading it. My primary objection was to the article's use of the adverb "often" in regard to Fundamentalists, i.e.
To avoid this conclusion, Fundamentalists often assert that Mary did not carry God in her womb, but only carried Christ’s human nature.