Did you try it anyway? It’s probably similar in concept to using hotkeys. If you select something in the overview, and then click out of the overview, your hotkey will still act based on what was clicked in the overview (it has lost its focus, but not its selected value)
You’re allowed to use the slash command, but there is no reason one would actually want to unless they were attempting to kludge together client automation.
What the slash command actually does is briefly queue the exact same function that is activated by the keybind for dock/jump/activate. You can make it last for a usable period of time by holding the enter key (I’m assuming this is subject to your held-key repeat delay).
For that function to work, the target must be actively selected. There are two main ways to accomplish this:
Hold the hotkey and click on the target in (almost) any context.
Select the target in the overview and press the hotkey while the overview still has focus.
Baby’s First Bot Author Elite PvP Pro here is trying to click the target on the overview (which the client does for you automatically when you jump a gate and have a destination set, as it happens) and then use the slash command to execute the function, but entering the chat window steals focus from the overview, so the function does nothing, just the same as when the hotkey is used without an active selection.