It remains the most widely cited theory in the field of language acquisition. Unz misspells Jim Cummins' name. This only holds for early stages. In the long run, those who begin second language acquisition as children do better than those who begin as adults. Because the demands of the curriculum are much greater for the older child, it typically takes them longer to reach grade level.
Older children have more to learn.
Children learning English should be exposed to minimal English until 9 or 10 years old. My position has always been that children should be exposed to maximum comprehensible input in English from the beginning. I have never supported delaying English for any reason. Mr. Unz should know that this is my position. I told him this on the telephone, and discussed it on KCRW, in response to his statements on the same program.