"I have backed up my own cartridge, and have got it running on an emulator, but unless Goldlocke says so it will be staying with me and won't be shared."
So you're just openly participating in artificial scarcity. No one loses if this is released. Goldlocke won't make a dime whether or not it's released, the objectively correct choice is to release it.
"But to answer your point.... don't worry, it won't be lost."
Unless you lose the digital file. The more copies are made in separate places, the less chance of it being lost.
"Also here is one piece of good news. the Turrican team seems to have given its blessing with some merch sent to Goldlocke, so perhaps the worry of DCMA takedowns is alleviated, and gives the possibility of the rom being released in the future."
Who gives a shit? Leak it without permission.
Goldlocke has updated the ROM download with v1.1 which looks to be the full game and that now works on emulators and generates a save file, so, thank you for that, but i guess now you could expect to see Dottie Flowers ending up being produced on fake cartridges.... so your scarcity issue is now no longer an issue