I consider this under the general category of condemnation for bad behavior--just appropriately gentle condemnation--unless you literally never dropped any hints at all when his behavior started to veer in a more problematic direction, and he'd only ever find out long afterwards when you reviewed behavior for the day. Maybe you really didn't give him any clues at all--maybe he needed that much space in order to have any chance of modulating his behavior. But if so, it sounds like an unusually difficult case.

Not all condemnation needs to be shaming and isolation! Indeed, that is almost always way too far. For instance, it's very hard isolate someone without it seeming like a condemnation of them not their behavior. One can communicate disapproval (a gentle form of condemnation) by withholding a star. It's gentler than taking away a thing because even if one has been anticipating the star and therefore has partially discounted the reward emotionally (so not getting it is scored emotionally as negative), it's not as certain a loss as definitely having something and then losing it.

That an expectation of condemnation works is evidenced also by the fact that most children older than toddlers have a considerably higher threshold they need to reach before they'll throw a tantrum in public rather than private, save if they've learned that their parents will give them anything to avoid a tantrum in public. Public disapproves.

I'm glad you found a method that helped your son!