I've just read the conversation. I totally agree. LCPDFR should definitely be open-source to let the community improve the mod. Speaking of some other reasons to make it open-source, GTA IV community is actually enormous and actively growing. I keep seeing people trying to play LCPDFR. Some can play, some run into issues which need to be fixed. Since there are people willing to help with those (such as the OP), why not just make it open-source?
Someone needs to host the source on GitHub for pull requests 'n stuff though if you're going to make it open-source, it would be hard to find one who you can trust and is willing to continue development of LCPDFR.