What do you mean by "legitly bumped topic at the topic." What is legit vs not legit bump?

There is a bump button that will appear after 4 hours, or you can simply type whatever you want after 4 hours to bump your topics by site rules

So if you respond to a topic before the 4 hours, it does not bump your thread to the top? One would have to have waited 4 hours to have the thread bumped?