This NPC can sometimes become bugged and won't give out the quest. One way to solve it is to kill him, and when
he respawns again, he is able to be hailed as normal. Be mindful though, that this gives you about 200 penalty in your
Qeynos Guard Faction. If you don't want to lose faction, get someone else to kill him, or wait until the server restarts
as that also seems to help.