I am not long gone, as it was mentioned PRJ's tool worked well so that was the end of that
While I am glad you are still here, you might be gone in 5 or 10 years when people are still flashing and tuning these cars. If you put it on github then people can contribute to it and improve it, and it will always be available.
If the issue of putting it on github is that you arent very experienced with github, I would be glad to upload it and maintain it. You would just need to get me any changes you make so I can keep the source up to date.
If the issue is that you want to keep it proprietary, I'd like to ask why? You have more chance with a donation link on git than anything to make a profit off of it.