firstly, the posix SHELL is not at all unfriendly (terminal != shell), and introducing it earlier can only be beneficial. If you get scared by a shell, you probably shouldn't be in programming.
And actually, for better or worse, many of us as kids learned programming in "unsafe" environments. So the onus is on you to prove that the alternative is better. Surely a study could be made.
I think starting with something approachable like Scratch then advancing on to a posix shell in Ubuntu is a great idea, but I take issue with the attitude that if a child is scared by a shell they should not learn to program.
Anyway, the kid doesn't have to know that the shell isn't prerequisite to play games -- until they figure it out on their own. My point was more that children are adept at overcoming obstacles that stand in the way of play.
I agree with that point entirely, but that does not mean that all children will overcome all challenges. My point is that we should not give up on a child just because they struggle with a shell. The reason I think shells are not the best introduction is that they cannot be figured out by exploration. They require specific knowledge that cannot be deduced because it is fundamentally arbitrary. That information can still be found online, so it is not impossible to discover, but I think it is ridiculous to give up on a 7 year old because they did not like exploring a shell.