I think your son will likely be admitted to Penn if he applies ED to maximize the legacy boost. He has stellar grades and test scores and his ECs show a commitment to service which Penn loves. I don’t think a lack of business ECs will hurt him either. He will need to write a compelling essay that shows the AOs why he’s passionate about Penn aside from being a legacy.
I believe he’s a strong candidate for RD too, but his odds of admission decrease without the legacy boost. If he likes both Harvard and Penn equally, then it’s down to game theory and you’ll have to decide which school is more likely to admit him.