You're talking as if the game is already done, it's fun, but is held together with duct tape. I'm questioning whether the game will ever come out at all.

He's painting a picture about what the game will be like; his users aren't savvy enough to know whether he's going to be able to make it a reality.

If something stands out as a red flag, bringing into question whether he's got the ability to produce the project he is taking money for, it's absolutely appropriate to point it out.

I've been in the indie development scene ten years; projects like this are a dime a dozen, and a single digit percentage of them ever get finished.