I agree that your child should report this, but not just to the RA. RAs are students. They have very little power and authority, no matter how well-trained and mature they are, and they have only slightly more life experience than the students they are “RA-ing.” Mental health problems are above their pay grade and need to be reported to the first-year dean. Telling the RA is important, but it’s more of a courtesy than anything else. Safety issues, which this very likely is, need to be handled by people who have the power to do something.