But expecting to control your environment and context so that you are never bothered by others misfortune or negative experiences, is echoing the mantra of the permanently positive, boundary setting brigade, hence the references to the self help guides!
Have many people actually said anything about being permanently positive though?
Even people who understand there's likely reasons why the colleague might feel that's way seem to (on the whole, and me included) think they've gone about it the wrong way and have overstepped.
There's no need for anyone to be permanently positive. There's no need to hide grief.
It is entirely possible though that this situation is affecting the work environment though, not because there's a bereaved colleague, but because there's a friendship group whose behaviour and emotional investment is being brought into the workplace.
Take age out of it, if Person A who has nothing to do with Person B, they don't work together closely, Person B is in their office and is experiencing some personal issues, there's been an announcement of B's issues in team meeting so people are aware.
If A is doing their job and has nothing to do with B, they aren't coming into contact with B, and B is doing their best in a difficult situation and not offloading around the workplace, then A is not going to be aware of what is going on, or the regular crying or anything because they don't come into contact with each other, and any support B has is very private so nobody else is aware. A wouldn't know anything to make any comment (however misjudged a comment might be).
The fact that A knows so much AND has ended up in a position where they feel it's affecting the workplace doesn't mean B has been unreasonable or that B should hide their personal situation. It does suggest that B's friends are not being as private as they think they are and it does suggest that the friends and their focus on B's situation is affecting the workplace.