You know what, if you have hesitation about posting something, then you probably shouldn't. It's one thing to have a specific concern about his project, but it's quite another to call into question his skill as a programmer and indeed quite arrogant to assume that you know what it takes to build an OS.
There is a big difference between saying "You don't have what it takes" and saying, "I think the obstacles you face will be very large, good luck!"
There is a big difference between saying "You don't have what it takes" and saying, "I think the obstacles you face will be very large, good luck!"