There’s no reason why he couldn’t take a year’s worth of transferable basics at a community college…four point them…and try again for UCLA as a transfer student.
Telling your kid “it’s just the luck of the draw” is NOT helping him.
There is a reason he wasn’t admitted and you know what that reason is: His grades didn’t match their selectivity.
So,be honest with him. His grades were not good enough. Tell him to put his nose to the grindstone and four point a batch of transferable classes that apply to his major, and try for UCLA again if he absolutely HAS to have THAT school. If he’s willing to do the work and make the scores, it’s still possible.