God judged Eli both as a father and as high priest for failing to restrain his wicked sons

Mike says the answer is both. Eli's sons were priests (his sons and his subordinates simultaneously) who committed grave sins including sleeping with women who came to offer sacrifices at the tabernacle in Shiloh. Eli failed to hold back his sons in both capacities — as their father and as their high priestly supervisor. Mike draws a contemporary application: leaders who hire family members (nepotism is acceptable up to a point) but fail to discipline them for conduct they would never tolerate in anyone else repeat the error of Eli.