There are two types of dependents, "Qualifying Children"(QC) and Other ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit and student status test, a relationship test and a residence test.
Since he was not a student, he can't be a QC. So, there is a $5050 income limit for a Qualifying Relative, so he can't be a Qualifying Relative, either.
