I don't know that there is a big need to think deeply on this issue. This message is only going to show if they are using a version OLDER than what EMC is on. So if they are running an old version of Minecraft, then they should know how to run the current version of Minecraft.
Good points. I don't think it matters too much, though, because the link you get when you try to connect is clear enough (or should be rewritten to be so), and as chickeneer said, people that are not on the latest version will probably know how to change version.
