First, have your son also take the SAT. Some students do better on that than the ACT.
Second, a community college is a good alternative. Your son can get his general education classes done. He also may find it opens new doors to other schools.
Third, my nephew graduated from a liberal arts school in Virginia with a degree in computer science. He was an okay test taker (compared to his kid brothers who were exceptional). He has done just fine in terms of landing a very nice job with a Northern Virginia company.