@ 10v - This thread is only to be used to report forum related issues, as outlined in the opening post. There is nothing that the F Mod team can do about situations that happen in game. If you are having an issue with a particular player in-game, then either attempt to resolve it in-game, or agree to disagree, add them to your ignore list and move on.
Different friend chats are set up for different reasons and it is up to the owner of each fc what the rules for their channel are. If they want to restrict it to only friends, or to players participating in a certain minigame or event on a specific world, or whatever, that it their right. As long as they are not discriminating based on real world criteria such as age, race, religion, etc. or engaging in activities that are illegal or against the game rules, they may use their friend chat as they wish. And they decide who they want to rank and what controls the ranks are given. If you are unhappy with the way a particular fc is run, again, take it up with the owner in game, or find another fc.
Nic - I appreciate the concern for your friend, but there are many potential causes out there of a player having a disappearance from the game, such as an internet outage or computer hardware failure. Unless there has been some clear indication of a player's safety being in jeopardy, there really isn't much that Jagex can do here.