Hah, I was just about to say that exact same thing. It's the sort of thing that definitely makes me cringe when i see it, but hey, it's under the size limit (you said 43MB, but I think you meant 43KB).
I ran the converter myself and I have to say, I was impressed at how accurate it reproduced the original raster image. Of course, I'm sure it helps that the original is already limited to 16 colours. So, really whatever helps speed up the workflow.
EDIT: Also just realized that because the dithering is baked in, ScummVM's undither option won't do anything. Which I personally find a shame (although I think I'm in the minority with that opinion). Regardless, in a project like this, I do still believe workflow and time efficiency is king. Really solid looking background, btw. Excited for your progress.