No, you are wrong. The Tweet has been deleted.
I'm assuming the reason you can see it is because your browser saved a copy of it in your cache from when you visited it the first time. Once your cache expires, you won't see it anymore. That depends on how long you have it set for. I used to have mine set to save for 1 year, but that ate up a lot of HD space, so I stopped doing that.
There are actually a number of ways to see/recover a deleted Tweet, but I'll let you figure that out as I have no desire to have anything to do with Twitter.