I'm going to be completely honest: as much I would like the idea of being able to ghost clear delayers, there are few unfortunately major problems that would make this hard to implement.
First, many people have different interpretations of what's considered "delaying"; some are lax about it and consider only going off into an area to hide and not do anything to be true delaying; others however are incredibly impatient and consider even just trailing off for a few seconds to do something "non-rebelling" enough to be considered delaying. Basically, we as a community do not have any sort of general consensus on what is enough to be considered delaying. My biggest concern is that the latter group in particular would use this change to ghost the immediate second they see a RED start "delaying", even if it's just trailing off for a few seconds. Adding on to this, there are many (MANY) situations where REDs (or BLUs) aren't actively TRYING to delay, they're just simply lost trying to find a guard to kill (or vice versa).
Second, even if we try to set a certain amount of time delaying where a RED can then be legally ghosted, this will be difficult to enforce, most especially when there is a large amount of REDs alive, most prominent when the warden dies prematurely and it becomes a freeday, particularly when it's last guard. There's no way to spectate all the REDs at once so if you are spectating one RED and choose to spectate another and see them hiding in a corner already, you aren't gonna know how long they were there for.
If we can somehow find a way to implement this while figuring out solutions to curb (or ease) my above points I'm all for it, but as it is now this would be too hard to enforce.