Looking at matters from the other side of the fence

A friend of mine was telling me how he felt bad because he thought he'd disappointed his thesis advisor by not staying in academia. I think he means more than just a passing professional disappointment.

My partner has just been assigned several masters students is working with them to come with problems. I'm finding myself reminding him that the traits that he wanted in an advisor are not necessarily the traits that work well when advising the generic student, and that a masters student's goals are different than a PhD candidate's.

As a grad student, certainly in the early stages, I thought of my advisor as something akin to an academic deity of the ancient Greek variety. He had his unique temperament, but was great and powerful. By the end of my experience, he'd humanized quite a bit in my eyes, though I still have a great deal of respect for him. I understand my friend's urge to want to please his advisor. His advisor is his mentor and his guide, and a genuinely nice person. Of course he wants to make this person happy.

But (correct me if I'm wrong, wise readers) a good (ideal) advisor approaches his students with a certain detachment. After all, this is a professional relationship. The emotional attachment to the student's work should go about as far as one's emotional attachment to the research in general. If they choose to become friends with a student, that's beyond the scope of the professional relationship.

On the other hand, watching my partner navigate the path to advising students successfully, I'm realizing how much the shortcomings of advisers are due to the fact that, in spite their academic prowess, they are human beings. The quirks that make up one's life and research through landing that first TT position do not disappear with the appearance of a student. In fact, they probably get further ingrained the older one gets. Everything in the previous paragraph is like solving freshman physics problems assuming a spherical cow.

On deciding to sit on a thesis committee

Here's an interesting situation:

A PhD student approaches you to be on her committee. It is her final year. Due to having the misfortune of having several committee members leave for other jobs over her tenure at the university, she does not have a full committee this late in the game. In fact, due to said attrition, finding people in the current department who are a good fit with her research interests this late in the game is difficult.

She approaches you to be a committee member. You study the general topic that she is interested in, but your expertise runs in problem A. She is interested in technique B. You think that the best papers are those that use technique B, but also address problem A. This is a commonly, but not universally, held belief. However, up to this point, no one has really talked to her about problem A. Most of the members on her committee, now and in the past have all been interested primarily in technique B.

You learn that she has is doing her PhD in order for her to qualify for a promotion in a job that she will return to next year.  Do you:

1) say you can't be on her committee, because you don't think her dissertation can be fixed to the point of your approval in the time remaining?

2) agree to be on her committee, and ask her to do all the work you would like to see on problem A before passing her?

3) agree to be on her committee and ask her to learn about problem A, and include a "further works" section detailing possible ways of addressing problem A?

4) agree to be on her committee and lower your standards for a good dissertation in light of the fact that she's been screwed over so many times, and  she has a job already?

5)Something else completely?

Not having a lot of experience with dissertation committees, I have no idea what to do, though I lean towards 3. What say you?