Killing the 4 scimitar kits in the valley east of musslaklan youth will raise faction with most of the factions in the Trader camp, but not with the Trader himself. I wondered why he was the only one that wasn't neutral after a LOT of dead kits, so it is doubtful that he is on any of the positive faction hits from the kits.
But after a few handfuls of morvalt ungdom he went neutral and I could continue in the Ibicus quest.
So... Kill morvalt ungdom to be sure to get on the Traders good side.