I think it’s in the nature of Go that many things depend on tempo and not just on the configuration on the board.
Whether or not you can win a ko, whether or not you can make life for all your groups, whether or not you’ll be able to take advantage of the apparent potential you have in the early game, they are all things that often depend on the exact order you play your moves, on how well you can take advantage of sente, or in other words, on how much tempo advantage you gain or lose.
As the game gets closer to the end, there’s an “optimal order of moves” that becomes more and more clear, and better players will (or would) of course be able to start seeing it much earlier. Though the path was probably always there.
(It changes during the game because the players, including AIs, can’t see it and just make guesses, but there probably is an optimal game of Go for any position.)
Anyway, I think it’s in the spirit of the game to respect the importance of tempo management, and I think it’s very much in the spirit of the game that “passing” not be considered an actual legal move, but only an artificial convention.
Consequently, I think it’s also in the spirit of the game to let unsettled groups, and perhaps even sekis, be decided by the natural flow of tempo of the game. Whichever player happens to have the move that will kill their own stones has the burden to play it or accept that those stones are dead.
Plus, unless I hear a good argument against this, I don’t think it makes sense to assign the burden of proof and/or the obligation to play first to either “the player who thinks their stones are alive” or “the player who thinks the opponent’s stones are dead”.
In the end, both players are simply claiming an area on the board as theirs, there’s no qualitative difference and no reason to give two consecutive moves to a player whether they want it or not.
As I said before, I recognize the use for rulesets in situations where games “need” to have an official result, such as tournaments and online play, and “playing a game through” is understandably considered a waste of time – but I will never take that to mean that rulesets have any authority whatsoever on what “playing in the spirit of the game” means.
Anyway, I want to make it clear that I appreciate that you’re taking the time to discuss this with an inexperienced player, even though you haven’t convinced me yet 