I also have never heard of the apex fallacy, ... is there not a potential for it to be valid?

I say yes, lots of unconventional explanations are potentially valid; they don't self-contradict.

To decide if it is true, we can follow b_b's suggestion and look for evidence. Looking for evidence isn't any harder than looking for quotes and theories and analysis that support our idea, and we might even find evidence that improves our understanding of the real world!

Suppose we find a pattern like this:

Men hold the highest positions of power in politics and commerce, but just below the top level women hold all the "middle management" positions. You hardly see men again until you get down to menial positions. Since leaders depend on underlings for guidance, and there are far more middle managers than leaders, women hold most of the power in this scenario.

I suggest you try it, really! We learn a lot more by reading about the world than arguing.

I'll try it for where I live (I am searching as I type this, and intend to share what I find whether it confirms my current belief or not).

In the United States, the highest political office is the President. It's a man. Next, symbolically, anyway, is the VP. He's named Joe.

A photo of the president's "senior advisors" caught attention for having 90% white men. The cabinet appears to be majority male.

On to Congress. A PDF says 104 of 535 seats are held by women.

On the business side, women represent 4.6% of CEO positions among Fortune 500 companies.

Looks like the national apex is pretty clearly male dominated.

In my state, the top government positions are held by three men. The House of Delegates has 16 women and a much larger number of men. The governor is male.

The company I work for has a male CEO, a male president, and a management team of seven, all men.

The city I live in has a council of two women and five men (not counting the clerk).

I find that I did learn something by looking at evidence: the pattern of leadership is more skewed than I thought. Of course it's possible that my location is unusual.

To make the apex theory work, I would reword it like this:

If you throw a dart and look at the organization it strikes, you will probably find more men than women holding leadership positions in that organization, regardless of the scale of the organization. Yet women really have all the power, because "The man is the head, but the woman is the neck!"

It's not quite as convincing that way.