Well, let the man give you his own answer:
-10th Symphony (1964): It is a lazy myth to claim that Mahler’s last score was unfinished. There are nine valid completions, none more exciting than 25-year-old Simon Rattle’s 1980 account in Bournemouth, England (EMI)…
Simon Rattle, so young, rattling everyone...
And Mr. Lebrecht should know: have you read his book on conductors?… weell, it will be a subject for this blog, without a doubt, because he shares some serious info on the matter… 
