What is the AVG GPA from Purdue Engineering Graduates vs. other top engineering college grads?

My son is interviewing for a paid internship and just found out that a “minimum” GPA is required. He has an outstanding resume with completing 3 paid internships before his sophomore year and shows a lot of great leadership. Don’t employer’s know that Purdue University is one of the top 25 colleges with the hardest grading and Purdue being #8 who does not curve their grades? This employer requires a 3.25 and he has a 3.1 GPA. It appears he will be passed over just due to his slightly lower GPA than the requirement. How can a student “justify” or clarify their GPA from Purdue on their cover letter perhaps without making excuses for their GPA. Ideally, it would be great to know what the average GPA is at UC Berkley (or other Engineering schools) vs. the average GPA at Purdue so Employers understand his GPA is good and worth the additional time to look at the resume. Any suggestions?