In general? Ren'py. Unity would be more than okay if you're able to make a full game out of it. It's more lively and has more options than Ren'py, but Ren'py is so easy to work that you have to actively work to fuck it up.
For Pinewood? Unity.
If doing things properly, emphasis on properly, either works, depends on what you need. I agree that for pinewood unity is the way to go, but the way it was done is not good. So far the game is on so small that you might not see to see how wrong things are done, but there is a reason why this hasn't been scaled up or done differently, he basically capped his own legs already at the start.
It's not really fair to compare unity with renpy either, you could compare renpy to unity+fungus, fungus is sort of the unity equivalent of ren'py, made for making visual novels, there are other VN toolkits, or assets as they are called in unity, that people use. This guy uses Utage for example, another similar thing that is "visual" game development, you drag and drop things and use sliders and buttons to make your game basically.
If you just want to go for the basics, and you are happy with what ren'py offers out of the box then, i don't think it matters if its ren'py or fungus or utage or whatever. Usually however you reach a point where you do not want something out of the basic toolbox, and then you are fucked.
This developer doesn't know programming, so by switching from unity to ren'py, while some things may be easier, some things is going to be a lot more difficult and eventually he will give up, or just get a developer to help him.
I'm sure that the developer has panicked for a while already about the future of the project, and has probably made peace with the fact that people will still pledge no matter what, and just ride it out.
People are always going to love these games that uses a famous intellectual properties, and in this case, there's a lot of different ones, for maximum hype and exposure.
/A