Apparently summer school is chock full so a lag class many be his only option.
Make sure he sees his academic mentor, has a complete study log and a record of when and from whom he sought extra help should he have to go before an ARB. Yes, advice from an upperclassman or the company academic officer is good too. In the meantime, if he is going to be home for the month of July try to get him into a similar class as remediation at a local college (he should be able to audit the class but you will still have to pay for it), or get a tutor to work with him individually.
Good Luck