That's why our paper "Combinatorics of Go" assumes the so-called Logical Rules at http://tromp.github.io/go.html, which do end a game on consecutive passes.
The reason that rulesets in the Chinese style branch are more amenable to mathematical analysis are that you can play the game until you have an unambiguous result about the life or death of a group, and thus these rulesets usually involve simply resuming the game and playing it out if there is any dispute about whether a group is alive or dead (or, for the logical rules, don't involve resumption at all, you just play it out and score it as is after two passes, with all empty points that reach two colors being counted for no one; since in area scoring games, ending the game before that point is mainly a convention for human players who don't feel the need to play all the way to the point of killing obviously dead groups).
Under Japanese style rules, playing within your territory to kill a disputed group may reduce your own score, so rather than just playing it out to the end, there are an elaborate set of conventions for determining the life or death of particular shapes. This elaborate set of conventions is much more difficult to represent mathematically.
The American Go Association rules of Go have an interesting hack to allow you to use Japanese-style territory scoring, but wind up with the same result as Chinese-style area scoring would give you, by having you actually give your opponent a stone as a capture when you pass, plus making the game-ending passes be two or three passes such that each player has the same number of turns. This preserves the benefit of area scoring, that any dispute on life or death can be resolved by resuming the game and playing it out until the situation is completely unambiguous, while still allowing the somewhat easier method of counting that territory scoring provides (filling in liberties with captured stones, and then just counting the remaining territory, and thus having to actually count to a lower number).
The Tromp-Taylor rules do make some adjustments for the sake of making it even more amenable to analysis that most other rulesets do not, such as allowing suicide. This doesn't actually affect the strategy in very many games, as it's very rare to encounter a situation in which a suicidal move would be the best choice, but it tends to make analysis a bit simpler as there is one fewer constraint to worry about. I feel like allowing suicide is more elegant, but it is only allowed in a few rulesets.
It is unfortunate that for such a simple game, there is no one agreed upon worldwide rule set. There are a couple of different parameters that you can tweak in a ruleset that give you a game that is very similar, but different enough in a few corner cases to make them different games; territory vs. area scoring (and with territory, the large number of conventions on life and death you need to make it work), simple ko vs. situational superko vs. positional superko, suicide vs. no suicide, counting points in seki, and komi (number of extra points for the second player to make up for the first-move advantage).
I'm afraid to ask for pointers to understanding that statement, as it would mean spending hours pouring over the details (and likely writing & running software to analyze it) just to understand a ... 2x2 go board.
Seems to fall into the category of "grand unified theories" in any topic, where prolonged advanced study of complex systems tends to lead students thereof to develop zen-like simple-yet-profound expressions of the subject.
Now I want a 2x2 go board. "What's the point of that?" "There are a third of a trillion possible games that can be played on it. Care to try one?"