Why are you trying to push him? If you really want it that bad learn Rust yourself.
Greg made it clear that he wants GT6 to be as close to “done” as possible before going further with his game and he got sucked back into GT.
Also he stated that he isn’t really inspired enough as of late and I can understand that.
Don’t try to push him. I think even he doesn’t know when he’s going to get started for real 
. It’s going to happen just have patience 
Patience is a virtue (although I lost some of that as of recent. I also want mechaenetia but don’t want to really force anyone into anything)