Journey begins
Esdras talked with David and he jumped at the opportunity. Of course, Esdras didn't tell him that they were escorting the crown prince.
He did as Ron ordered and told him that they were transporting important items to the capital, which was not a lie, technically.
After all, the prince was taking an important royal relic to the capital.
Interestingly enough they were not told anything else about the item, in normal circumstances, it would not have attracted their attention.
But the fact that the higher-ups seemed to dismiss it, and emphasize it simultaneously gave him the impression that it was just as important as the crown prince, or perhaps even more.
In any case, having observed that much, he decided to curb his curiosity. Too many questions could get on the nerves of the higher-ups.