you’re not accounting for why CG implemented ties to work this way. They likely did it because it is more likely to favor people who choose to spend money on the game
No. This is not why. Early on there was pressure to not relic up any toon you weren't using heavily because you were penalized with harder matchups based SOLELY on GP.
Now, later they changed that to the skill rating, but when CG realized that people were being rewarded for NOT investing in characters, they decided that was bad for the game. They thought that improving your characters should never give you a disadvantage, and when they changed GAC they made it very clear that they were giving ties to the higher GP player so that people would not gain an advantage keeping trashy characters like Bodhi Rook at LVL1/G1.
If you gained an advantage in GAC by keeping your GP low but your guild gains an advantage in TB by each player maximizing their deployable GP, then personal success in GAC and guild success in TB would create conflicting incentives, which would also create guild strife as some players hurt the guild by minimizing their GP to maximize their GAC chances.
It's not directly about money, and the reason isn't a mystery -- it was just announced so long ago that lots of current players missed it (and some no longer remember).
It is unhealthy for the game to give players an incentive to keep toons g1/L1, and the tie mechanism reflects that.
That said, they also put a lot of scoring details in GAC to minimize ties so that this wouldn't come into play often -- and it generally doesn't. 3 ties in GAC is some really bad luck and I'm sorry about that.