AI pays for tech with only 1 turn left

[playshogi]

I found that passive espionage is useful for tracking when an AI is only 1 turn from discovering a tech. If I have the tech to sell, they will always give me gold for it. Maybe, not all of their gold, but some. They shouldn't give any for discovering it with only 1 turn to go.

 

[H&K]

Why not?
Thats one turn closer to their next tech