1. Pretend that the number in the Legacy Point crown changes to 0 for the technology that card is played on. So it does score but it scores 0 points and its prerequisites score like normal.
2. Pretend that the prerequisite is no longer written on the card so it is not required and will not score points. This can be used agressively to keep an opponent from getting points as a lot of prerequisites will score more for their owner than higher level techs.