I'm all for appropriate limits. The "They'll let you know what they're ready for" is more about whether it's okay to answer a kid's questions or do a certain level of math with them. (And I think that's how Austin intended it.) If they can form the question, then I think they are ready to dip a toe into learning that thing. If Starfall interests the child and YOU are okay with the concept of computer time for a young child, then it's probably okay, within limits.
That doesn't mean that the child should get to make all the decisions about YOUR day or about computer time. You're still the parent and it's okay to set appropriate limits. I can't imagine anyone here would say otherwise.
Child-led learning doesn't mean that the child is the boss! Just that you don't have to wonder if it's okay to answer his questions or let her read if she wants to.
