This old man is a noble from a neighboring kingdom. In the grand scheme of things, he isn't very important and was sent here to capture the miracle spider monster. Really, the other nobles that sent him here don't think he can actually accomplish this feat but are hoping his abrasive and "better than you" attitude will cause the local lord to do something that can give the neighboring kingdom a reason to invade. He has forced himself into the lord's hospitality and made several passes on his wife by this point and I think he even offers to buy their daughter. Guy is pure scum.
But because of his position and the tact of the local lord, he has the run of the town.