I feel like this "problem" if we're going to call it that has a reasonable enough solution that "fixing it" isn't worth the time investment as fixing or adding much more important things to Toribash.
As many people would infer, like yourself, simply spectating until your back is ALMOST as useful (it doesn't have all the same perks, else you wouldn't have made this thread. Unlike most Suggestions by most people, I know for a fact you're not dumb and you know how... shit in life works).
So... a possible idea to keep in the back of the brain for the future, but I think people would agree that there are some higher priority issues or features that Toribash Development should be cracking on over this one.
In terms of abuseable nature: I don't see anything you could do outside of uncomfortably rushing people who thought they had more time, or antagonizingly target one player in particular. Both of which can be done with essentially the same level of annoyance by just spectating anyway.