What major ? What level math ? Where is he likely to attend ?
There are likely strong substitutional schools with better odds.
If he’s ok with a rejection, then no harm.
The four schools are very dissimilar. If he wants to apply to just one, hopefully he can narrow based on - for example, UT is very urban. UIUC is in a small city with not much around. UMD is a burn of Washington.
If USC is So California, it’s a private ($95k) just off downtown LA with not the best surrounds. If it’s South Carolina, it’s smack adjacent to downtown in a capital city that’s not Austin but with plenty happening.