On blame

I've been interviewing students the past two days, and one of my coworkers sat in to provide feedback. This coworker (M) and I have never really seen eye-to-eye, but I never butted heads with her, either. However, after our third and final interview this morning, she casually mentioned that she has been having problems with one of our current students (A). M explained that another one of our coworkers (Y) has been "talking and talking and talking" with A, keeping A from doing work. She blamed A for being "too sweet" to put her foot down, and she blamed Y for monopolizing A's time with conversation.

Here's the thing: our student assistants assist EVERYONE in both business offices. Not just me, not just M - EVERYONE. And Y will very frequently have a task that requires student assistance, tasks that require explanations and conversations. Here's another thing: not a single soul, aside from M, has ever complained about any of our students. In fact, I get compliments and rave reviews on a regular basis; everyone else who has interacted with our students praise their diligence and hard work. And I've certainly never heard any complaints about our students being "too sweet".

This isn't really a tip or a guide to interacting with other people. It's more of a question, honestly. I personally think M is too heavy-handed when it comes to our student assistants; I think she's taken on a role that her position was never intended to take. And while I cannot commend her enough for wanting to take on added responsibility, I am extremely protective of my students and my coworkers, and I cannot stand undue criticism. So what is the solution? Do I tell M to stuff it? Do I tell Y and A to stop conversing regularly? Do I train our students to put their heads down and work in silence?

My answer to the last question is a resounding "NO", of course. But I don't know how to tell M to lighten up, either. If you, the reader, have any ideas, please share.