It's true that your question was answered straight away. You asked, "do coaches push walkins through admission?" CabbageDad replied, "no". Done deal.
It's also true that the thread has meandered, and in the end you have said today:
Baseball and high school sports does not have to be just one thing. It can be a chance to play in college or it can be a chance to give a kid a leg up in getting into the school of their dreams. Even if that means not being likely to play or even being cut.
Going back to Cabbage's original response, the disconnect there is that players who are not likely to play will not get a leg up from coaches. They are on their own.
If that's the player's choice, fine. But it may be that there are other dream-worthy schools out there, perhaps at a different level of play, where the player would be perceived as an impact player and would get help through admissions.