I've seen Lampo open chests before, and gladly give up a cow piece (if one dropped) to the organ donor. In this particular case, I wouldn't blame him for not giving up a cow piece to the host of that game..... colorful their mouth is.

While I do frown upon people joining a public game and rushing to chests because they can, it isn't against the rules. Like Dante mentioned, the best thing to do is to make a private game and:

1). Clear chests real quick before asking a GM to announce it to the public or;
2). Ask a GM to announce to the public but make it clear chest drops are for the host. This way if someone joins this private game that was announced and breaks the rules, they can be penalized for their actions.