The rulebook is quite clear as to how Re-Building works. It was even clarified on the Spartan Forums long before it shut down.
You can only re-build a squadron if One of the SAS you had on the table at the beginning of the game has died. It doesn't matter if the SAWs are taken from casualties of another SAS as the individual SAWs do not matter for the calculation.
To quote the important part of the rule from the rulebook, word for word:
In order to execute a Re-Build Carrier Action, a Carrier Model must spend 3 Carrier Points to Re-Build a LOST SAS.
It goes like this.
You start with 4 SAS on the table. At some point in the game one of those SAS is destroyed
4SAS - 1SAS = 3SAS
At a later point, a Carrier Re-Builds a new SAS
3SAS + 1SAS = 4SAS
Later in the game 2SAS are destroyed (or lost)
4SAS - 2SAS = 2SAS
Then the Carrier activated and Re-Builds a Single SAS as it does not have the points to create 2 of them at the same time
2SAS + 1SAS = 3SAS
See? Its does not matter how many SAWs you have in your scrapyard. They do not even come into the equation. It only matters how many SAS you have on the table and how many you started with. You cannot have more SAS than you started the game with and that is because the rule says you can only rebuild a LOST SAS. Not half of the loses of 2SAS, but one full SAS that has been sent to the scrapyard.
There is nothing wrong with the rule or the rulebook. Your just wrong. The rulebook is clear and it has been clarified before. And it is not hard to keep track if an SAS has died. You just look for a tray in your Scrapyard.