You really think he is a good chap? He put a hit out on his own brother...
...who's a drunken idiot who was running the shop into the ground. Not that the guy actually says so, but it's pretty heavily implied.
As for the sabotage thing: I heard about that too, but I figured it wasn't actually going to happen. As a result, I wasn't surprised when that turned out to be the case, although I'll admit I was still a little disappointed as it would have been fun to be able to influence the merchants that way. It would have opened up some additional possibilities too, such as coercing the local merchants by threatening to cut off their supplies, or diverting said supplies from one Hold in order to inflate the stock and bankrolls of merchants in another. They could have even tied that into the Civil War quest lines, with missions to sack/escort supply caravans or blockade/resupply various villages/towns.