Please correct me if I am wrong but in order for this to work you would have to open up the browser and enter the original password into the first page before the other person changes the password, yes?
Because TQ uses multiple web pages for account verification they have to have some way to remember you from one page to the next. So it creates a session, which is basically just an entry in a database saying "This person entered the correct information on the 1st page and is now on the 2nd page". After the other person changes the password, your original session still exists because either TQ doesn't time it out or you can bypass the timeout by clicking OK to reload the page thereby refreshing the session and preventing it from timing out. So even after the person changes the information, your original session is still valid (because you already entered, what was at the time, the correct password on the 1st page) and allows you to change it back once you enter the correct ID on the 2nd page later.
Evil. :(
I only wish this sorta thing surprised me from TQ anymore.