Double Deac parent here, 2021 DD (classmate of @rickle1 's son) and 2024 DS.
DD had a comparable situation to your son. She was a little introverted and had a regular decision choice between Smith College and Wake Forest. In the end she chose Wake because she wanted to get out of her comfort zone a little. I don’t think Smith is analogous to Colgate, but Wake Forest really got her out of her shell.
Wake is a unicorn among colleges, an oversized LAC in many respects with ACC sports. I would suggest a visit and interview during a football weekend in the fall.