I don't think this was his goal-- he was trying to make a jab at Qi, even though it was a rather petty one. Maybe he thought it was funny, lol
We don't really know what he was trying to do. He could have been actually stealing it because Harvest likes to think of itself as a pure building clan, but the grudgery between us doesn't suggest he would respect even our motto, so naturally we assume he was trying to make fun of it or steal it to make us mad, but unforntunatly for him, spending a week trying to cast a group as a bunch of degenerates and then using that group's motto in your own group that you hail as the best doesn't really support the fact that the Harvest is the best. It made me laugh more than it made me mad, and I kind of feel bad for him that he thought it would be at all successful.
tl;dr: He belittled his own clan's topic in an attempt to troll [Qi]. He probably realized this, and that's why he's no longer using our motto.