Lol no one needs 20 seconds to analyze the whole board. You can make your move in under 10 seconds no matter what the position is.
I've played live960 against players ranging from complete beginners who hang everything to titled players, and trust me, they all move within 5-10 seconds, if not much more quickly.
And then - if I want to abort a 960 game, I have to wait longer, which isn't worth it, since I've had to abort before, and I don't want to get those flags if I abort manually. The current system is fine, and preferable.
For 10|0, the game auto-aborts after 20 seconds if no first move played. Ofc, this is very forgiving for standard play, 20 seconds to decide between e4, c4, d4, etc.
But with Chess 960, every new board is something completely different. You have to analyze the new board, look at which side is easier to castle, which pawns you want to move, are there any pawns hanging that you can attack right away. Sometimes this takes more than 20 seconds, so I think you can make the auto-abort system more forgiving for Chess960.