That looks like it'll work, but there's something that might be interesting and will hopefully be helpful that I'd like to tell you. At the moment, because you're using an http://www.creationkit.com/ObjectReference_Script auto property that I assume is set in the Creation Kit. This approach will work just fine, but it's worth mentioning that it will also make your container permanently http://www.creationkit.com/Persistence_(Papyrus).
An alternate approach that you could try, if you want, would be to use a http://www.creationkit.com/ReferenceAlias property instead, and have an alias on your quest that points to your chest. So long as the property is filled, you can access your chest and everything's fine. The difference is that the alias is cleared automatically when the quest is stopped, and the chest will no longer be persistent.
If this quest never stops then that approach wouldn't really change anything, but I thought it was something that would be worth mentioning.
Also, just as a side note, because you only have one auto state in this script, you should be able to just remove the state and have the whole script exist in the default "empty" state.
Cipscis
Great to hear, thanks Cipscis!
So if I want to make this repeatable, for example, I have some activator with a message box that lets the player choose to go back to stage 30 of the quest, then I should add a line to enable the trigger box again during one of the earlier quest stages, since it is disabled here?