The problem I find with all of this is 2 fold.
First i don't care. Honestly I'm coming to play a game to get away from the realities of life and just have fun. Keep your problems to yourself. Asking someone to report someone is annoying enough and usually makes me report you. Firstly I'm not going to report if I don't see it. Thats just stupid. Second if its intentionally feeding or something and you don't think I can tell and ask I'm reporting you anyways. Its harsh, but its a peeve of mine in league where people ask for reporting. Secondly saying that your mom as it is completely unnecessary. Why would anyone even care about your problems? It sucks it really does, but no one here does. I have my problems and I'm not complaining to everyone else.
He is bringing his problems in. Just because someone tells him to get cancer (while that is just stupid), he doesn't have to bring up his mom having it. Since I'm assuming that the statement about cancer was not said in all, but the comment about his mom was. Meaning that he did bring his problems to the game. No one asked about his mother with cancer or anything. He brought that in. There was no need for that line at all.
Second, the amount of BS that gets spouted out in chats has me glossed over to all comments. Its the internet I see people all the time commenting on things that are flat out lies. I've seen people lie to emphasis a point to make them right or to make it sound worse than it really is. I don't see why I would take this any different. I have no proof or care. my usual response to this kind of thing is "k" or "sux" cause i don't really care about it. Promptly muting you after. I'm here to play a game not be your psychiatrist or hear your problems. Leave them out of the game and with family and friends. Not random internet strangers and then expect them to actually care.
Its a cynical look on life, but its how the internet has become and I'm not changing or going to look for those special real cases out there to spare a persons feelings. Recently had a guy I use to play with die. I only knew him as his IGN, but after seeing a number of the other guys who actually knew him IRL posted RIP as their status's. I'm not going around commenting on it or even changing my status. Its a personal dilemma and thats it. Not something the rest of the gaming community needs to concern itself with.