You’d have to check because this isn’t a specialty for me and I may get their athletic strength wrong, but I think Middlebury, Vassar, Brown (not a LAC but not huge and very good for students who want to explore multiple subjects), and Trinity CT all have solid men’s rugby.
A boy interested in philosophy&history + possible rugby hook would make for a winning combination at these or other LACs.
If he’s a rising senior he should contact the coaches ASAP with transcript and athletic video to see if they’d offer a pre read.
If he’s a rising junior he’s got time to create a good video.