The sentence really does not translate well. "There" on the end of the statement although written in Esperanto, when translated to English makes the word. "There" superfluous. Better translations maybe .... Look at that cloud, or look at that cloud over there. Or even, "Look at that cloud! There!"
Imperative of movement of the look from the place it is looking currently to the cloud. Should thus the original sentence rather be “Rigardu la nubon tien”, movement of look from one place to “tie” – which should have the “n” of destination movement.
An example of this in Mr. Stephen Butler’s example above: “Rigardu! Supren en la ĉielon! »
If you are asked to look at one place, it is necessarily because you were not looking at that place when you were asked to do it, otherwise, it would not be necessary to ask you to look at that place.
This inescapably entails a movement of where you are looking at. The movement is related to the look, la rigardo, not to the object looked at.
This remains true, whether you say "look into that place" or "look at something in that place." Hence, the OP is not correct and an "n" of movement is needed.
I would break the sentence down like this:
- Rigardu la nubon (kiu estas) tie.
You seem to want to break it down more like.
- Rigardu la nubon (kaj rigardu) tien.
This second reading is not possible because it forces "rigardu" to have two objects.
You could say rigardu tien al tiu nubo - but that's not what is being said here.
If you disagree strongly, go ahead and report it. I'm pretty confident that usage is on my side here, though.