A similar situation just happened in my own family! My adult brother lives with our very elderly parents. They recently posted photos taken of him posing with some casual acquaintances, standing directly beside each other. It all seemed so normal except when it occurred to us that this behaviour is completely unacceptable right now. I try very hard to be so careful, but I have to admit that until another family member pointed it out I hadn’t even thought about that! We are all in such an unusual situation, that we need to be understanding about occasional lapses in judgment. However, I’m thinking that those forgivable lapses only include not standing far enough away if you encounter someone on a sidewalk or while you’re picking up essential items at the store. Making deliberate decisions to get together with anyone who you don’t either live with or who are included in your (mutual) “bubble” is completely irresponsible .

It's micro-aggression. Things would scrappy if this were my family.

Are old enough to make their own decisions as to who they permit to come over for a visit. No, your brother probably shouldn’t be going over for a cut but if your parents were concerned they could’ve declined his request.

...with the sister in law.