This type of meta-gaming is the kind that a majority of players here don't tolerate. Derek and Lan, if you don't change the way you play, you'll soon find that no one wants to play with you.
Given your responses here, you aren't confused about how adverse your behavior has become and will likely not change your meta-gaming ways until you are forced so.
Because of that, I encourage every player that does take offense to their actions, to never join a game they have joined and if they end up joining your game, push for a cancel. As I stated earlier, most players will agree to your cancel once you explain why you want it. They may be annoyed, but eventually this will force Lan and Derek to change, or even off of the site.
You can also prevent this by always being the last to join a game. I personally try to make a habit of it, though if everyone did it, no games would ever be played.
And if Derek and Lan are doing this in an anonymous game, they should immediately be banned, as that undermines the very terms of an anonymous game.