With extremely rare exceptions, excellent basketball players who go to community colleges were not able to achieve the NCAA minimum for curriculum, grades, and test scores. If they had achieved the minimum, they would have gone to a four year college in the first place. We are not talking about a high hurdle to clear.
That is not the same as good students going to Holy Cross to earn a shot at Notre Dame. The basketball non-qualifiers couldn't even have been admitted to one of the schools that isn't eligible for the tournament because of a low APR score. Most Holy Cross students had choices, both four-year and community colleges.
Marquette and others will admit basketball players who barely meet the NCAA's minimum standards. Some of those schools, Marquette included, will and some will not admit jucos who could not meet the NCAA minimum when as high school seniors. Notre Dame requires basketball players to be well above the NCAA minumum before they'll be admitted. If they won't take the guys at or near the minimum, I don't think they would take non-qualifiers two years later.
Maybe there is an exception once in a while - a late bloomer academically, a late bloomer physically who chose a Juco to prepare himself for a shot at D1 basketball, or someone who was injured or had an illness during the key recruiting time in high school and chose a Juco after recuperating. Maybe. But there are very few of those guys.