Jack Taylor drove a tipper truck in the crash that killed Steven Davidson-Hackett in Exeter on 23 June, 2012.
He was given a Â£1,500 fine and a one-year driving ban by Exeter Crown Court for taking a vehicle without consent and drink-driving.
Ray Davidson-Hackett described the sentence as "a total disgrace, a total let-down".
He said: "My son's life is worth 1,500 quid. The courts have let us down, the CPS have let us down, and the legal system has let us down."
In 2013 Taylor, from Plymouth-based 42 Commando, pleaded guilty to causing the death of 20-year-old Mr Davidson-Hackett, but the Supreme Court later ruled that Taylor's drink-driving did not cause the accident and this charge and a charge of aggravated vehicle taking were not applicable.
The 28-year-old pleaded guilty to taking a vehicle without consent and drink-driving.
Judge Graham Cottle said Steven Davidson-Hackett's family and friends would understandably "feel let down by the criminal justice system" and he had "the greatest sympathy" for them.
Taylor had an alcohol level of 110 milligrams in 100 millilitres of blood - more than the legal limit of 80 milligrams - when his truck collided with the moped rider on his drive home from work.
Taylor had been driving at less than the 30mph speed limit when he collided with Mr Davidson-Hackett's 100cc scooter on a blind bend in the single track road, the court heard.
Mr Davidson-Hackett suffered fatal injuries as he went under the wheels of the truck and was dragged along the road and died in hospital later.
The father of a moped rider killed in a crash with a drink-driver says he feels betrayed by the justice system.