Is it a reference to Macbeth by those who haven't really read the play?
What does "Lady-Macbethed" in Chess mean?

Fair is foul, and foul is fair—The witches' philosophy of life.

In the beginning of the story Macbeth, Macbeth meets three witches. They tell Macbeth that he will become a king. The king at the time was Duncan. It so happened that soon after this encounter with the witches Macbeth was to receive Duncan at his castle. Macbeth relays the foretelling of the witches and the impending visit to his wife, Lady Macbeth who is very ambitious. Macbeth and Lady Macbeth sees this visit as an opportunity to get rid of Duncan and usurp the throne.
However, once Duncan arrives at their castle, Macbeth relents. This makes Lady Macbeth very angry. She says "When you durst do it, then you were a man; And, to be more than what you were, you would Be so much more the man. Nor time nor place Did then adhere, and yet you would make both:
They have made themselves, and that their fitness now Does unmake you. I have given suck, and know How tender 'tis to love the babe that milks me:
I would, while it was smiling in my face, Have pluck'd my nipple from his boneless gums, And dash'd the brains out, had I so sworn as you Have done to this." In other words, Lady Macbeth goads her husband into killing his liege, King Duncan, and Macbeth goes ahead and kills the king. After the murder, they both have a nervous breakdown and die. The end...
So Myra gave unsound chess advice to Colonel Hampton?

In the beginning of the story Macbeth, Macbeth meets three witches. They tell Macbeth that he will become a king. The king at the time was Duncan. It so happened that soon after this encounter with the witches Macbeth was to receive Duncan at his castle. Macbeth relays the foretelling of the witches and the impending visit to his wife, Lady Macbeth who is very ambitious. Macbeth and Lady Macbeth sees this visit as an opportunity to get rid of Duncan and usurp the throne.
However, once Duncan arrives at their castle, Macbeth relents. This makes Lady Macbeth very angry. She says "When you durst do it, then you were a man; And, to be more than what you were, you would Be so much more the man. Nor time nor place Did then adhere, and yet you would make both: They have made themselves, and that their fitness now Does unmake you. I have given suck, and know How tender 'tis to love the babe that milks me: I would, while it was smiling in my face, Have pluck'd my nipple from his boneless gums, And dash'd the brains out, had I so sworn as you Have done to this." In other words, Lady Macbeth goads her husband into killing his liege, King Duncan, and Macbeth goes ahead and kills the king. After the murder, they both have a nervous breakdown and die. The end...
So Myra gave unsound chess advice to Colonel Hampton?
I find your summary incomplete.

If you're not part of the solution, you are part of the problem. But I thank you, nevertheless, for taking the time to read my post and apologize for it's dificiencies.
"Life's but a walking shadow, a poor player, that struts and frets his hour upon the stage, and then is heard no more; it is a tale told by an idiot, full of sound and fury, signifying nothing." - William Shakespeare
Colonel Hampton snorted contemptuously. Senile dementia! Well, he must have been senile and demented, to bring this pair of snakes into his home, because he felt an obligation to his dead brother's memory. And he'd willed "Greyrock," and his money, and everything, to Stephen. Only Myra couldn't wait till he resigned; she'd Lady-Macbethed her husband's queen into this insane position.