I have two theories about this. After all, The Watchtower isn't exactly a paragon of journalistic integrity. The story can't possibly be verified, so why not say that she rejected these advances, and also rejected Spiritism? Thus the paragraph could end with a small moral victory. Instead her "yielding" is the end of the story, and we go back to "fallen angels."

1: It is a casual dismissal of women as being weak and easily seduced- especially by powerful beings. Kind of like Eve and the serpent. It is a reminder to the men in the congregation that they are in charge, and to watch out for slick charlatans who might swindle, or seduce the weak-minded women they are in charge of. You, as a man, are the shepherd of your flock. A point in the service where a husband grabs his wife's wrist, and gives her a threatening glare.

2: (Puts on tinfoil hat). It's code. It's a way to remind men in powerful positions (elders, etc) that they are a sex symbol. Women (or whatever object of your desire) will be easy prey for their charms and position of power. They will yield to you. And when they do, you will feel bad. But although you might feel like a fallen angel, at least you aren't a fool.

Conversely, (and out of the same reasoning as theory #1), it might be language with the intent of putting that thought into the woman's head. Basically it's saying Russel was a sex symbol. And even though the woman yielded, nothing more is said. Perhaps she confessed this, and was forgiven? Who knows? She didn't seem to get punished. So it's like a pervy attempt to get women to sleep with you. By suggesting that it is something that might just happen to you!