Those sanctions were widely ridiculed in the sports press.
Briefly, it is not uncommon at Caltech for students who have two or three possible electives that would fit into one open slot in the schedule to not register for any of them at the start of the term, and sit in on all of them and do the homework for all of them for two or three weeks, and then decide which to take. They then register for that one.
This practice is approved by the faculty and administration.
Caltech had just gotten a new head of athletics, and while reviewing student records he realized that (1) several students on Caltech teams had done this "try before registering" thing, (2) for those two or three weeks, before they picked and registered for one of those courses, they were technically, by NCAA rules, part time students, not full time students, and (3) they had attended team practice sessions during that time.
It's against NCAA rules to allow part time students on a team, including team practices. The new head of athletics reported Caltech's inadvertent violation of this rule to the NCAA, and also reported that all student athletes were properly full time before participating in any games, and that they would make sure in the future to not allow students to join the team until they had registered for a full load.
The NCAA response was to put more severe sanctions on Caltech than they had put on major athletic schools that had committed massive rules violations, such as fake classes and grades to keep players from becoming ineligible for low grades, bribes, and the like.
The sports press take on this was generally it was more evidence that the NCAA is incompetent and/or corrupt. The NCAA had been criticized for slaps on the wrists against those big schools with big money sports programs, so many thought that they came down hard on Caltech to try to look like they could be tough without the downside of damaging one of the big money making athletic programs.