This is a totally different issue; Wayland gives up the ability to provide user-aid that prevents an obvious human error. This is not really a security issue, it is a usability issue that can just happen to allow a user to make a security slip-up.
In exchange, Wayland gains… well, nothing really, the idea is that it’ll protect users from malicious programs peeking at other windows on their computer. But in that case situation is already FUBAR, there’s no way to protect a computer that is already running attacks locally on itself.
