The Machine Heart was not a new secret to the senior leaders of the Star Alliance. There were always a few races or individuals close to the Machinery Race in each epoch, having gained their friendship. However, there were very few who would manage to pass the test of the Machine Heart.
The requirements of the Machinery Race were too high. For these individuals or civilizations who managed to enter the eyes of the Machinery Race, they would usually be given some form of support or convenience, but only to a certain extent. There was no problem for them to recommend the individual into Heavenly Gates or further their relationship with the individual, but it would not break the rules of the Star Alliance for them. This was probably one of the reasons why the Machinery Race did not directly protect Earth this time.