SNOT-BOTS
Were Gaius and Lucius really this annoying? If they were, it's amazing someone didn't off them sooner. Suetonius tells us that Augustus adopted them when they were very young. He also makes it abundantly clear that Augustus never went anywhere without them. No wonder Livia kept a second house on the Palatine.

Augustus did dote on Gaius and Lucius. In his very own words, he writes in his Res Gestae: "My sons Gaius and Lucius Caesar, whom fortune snatched away from me in their youth, the senate and the Roman people to do me honor made them consuls designate, each in his fifteenth year, providing that each should enter upon that office after a period of five years"
(Res Gestae, II. 14)

So this scene does serve to illustrate Augustus' relationship with his two "sons". Pulman may have derived their snotty behavior from Graves (p.74), but Graves makes no mention of any incident with Drusus. In fact Graves states that the boys saved their insolence for people Augustus secretly wanted to annoy.