Has he try the ACT? Some students just do better with the ACT since it is a different style of testing.
Has anyone analyze why he is getting worse? Half of original score is a lot worse. There must be some reason. Whatever method he is using is not working. He needs to try something else.
As for what the colleges see, it really depends on the college. Usually you can find out on their web site. If not, call them.
Some colleges look at the highest score in one single seating.
Some colleges super scores, highest score in each section in multiple seatings.
Some colleges allow score choice so you can select what you want to send them.
Also most colleges app dealine is for the app only. The supporting material like SSR, test score can be a little later. Again, depending on the college.