If he hates grind culture, and he’s found a more “mainstream” U with a solid engineering program that’s affordable, I think you say “Thank you, Karma” or whomever/whatever you believe in and move on.
Purdue is a fine school and a great program but it’s not for everyone. And yes, the “grind” and competitive vibe are part of the culture. If he wants to explore other interests and have friends who are majoring in lots of different things, and doesn’t want his entire college experience dominated by the curve/the next exam/getting his butt kicked- Syracuse seems to me to be a perfectly acceptable choice.
I think Purdue can aptly be described as “you’re ecstatic when you’re done, but not always happy when you are there”. And I commend your son for having identified a school with a solid program where he might be happy AND ecstatic (at times) for four years!