Exactly.
Wherever he studies, the weed-out classes will be brutal. Pitt offers him a much better chance of continuing his major if he has trouble the first year.
Don’t get too excited by the differences in the rankings. Because ABET controls the content of engineering coursework, he will graduate with almost exactly the same engineering training no matter where he studies. Graduate admission is not dependent on where he goes to college. It is dependent on his grades in college, his GRE exam scores, his letters of recommendation, and any related work or research experience. The professors at Pitt have pals at good grad programs all around the country, and will be able to advise him on grad admission just as well as the profs at the other places.