I wonder if the author originally wanted to write simple gag manga because many things in this don't care about continuity. Like telling ossan he's contradictory for hating abuse of power but still asking for a plot of land. He bought the plot of land with the wyvern magic stone (which is probably worth a very large piece of land), so where exactly is the abuse of power here? It's nowhere, that's where it is. The author simply doesn't care, he just wanted to have the conversation, which while not humour, is similar to gag manga in the sense that it doesn't need to make perfect sense.
This is obviously just the more subtle part of it. The humour itself in this series is quite gag manga style, and has even had some tsukkomi in it. Perhaps he ended up writing isekai fantasy because it's easy to sell. Making a succesful gag manga must be quite a challenge in comparison.