They were just overconfident, after all. More troops, playing in the home field ... and the fact that pushing a night attack was quite hard in those days ( well, it is still hard nowadays with radios and night vision goggles, so imagine how hard it was to pull a sucessful night attack in those days ). Also it is unlikely that were just 60 horsemen pulling the deed ...
That said, for Romans of those days, virtue was defending the homeland and the clan. Scipio roasting the enemy would not be considered dishonorable ... maybe some would decry the fact that they weren't defeated in pitched battle ( Romans loved a good military stomp down ... it is not a acident they did themselves descendants of their god of war in their own mythology ) but again, burning some Carthaginians and Numidians after what Hannibal did would almost been seen as pious by the Romans of the day.
Later Romans, though ... let's say that later Aemilians shot themselves in the foot hard ( and even Scipio was not exactly a political animal, and got himself some problems later on the line ) and for a while talking smack of them was OK. Some of the later sources are less friendly to Scipio exactly because of that ..