You'd have to consider all those deals he passed up, as using his investment strategy, no? He may make 1-2 investments a year, out of maybe 200 investments available to him that he's analyzed. Thats still 200 investment decisions, not 1 or 2, which I'm assuming Taleb is using.
Wouldn't a thorough analysis consider four possible outcomes? The first event is the decision to invest (Y/N). The second event is whether their decision worked in their favor (+/-). (Y+, Y-, N+,N-) Y+ and N- are successful use of strategy. Y- and N+ are failed strategy. Same for Soros.
Example: Consider all of the investments that were passed up, that would have been terrible investments. That could be considered successful employment of an investment strategy. Buffett inherently (based on his style and risk profile) has a larger proportion of these.
You might think so, but as it turns out, no. Try simulating it.
That's the argument Taleb is making: that Buffett's success is weaker evidence for the expected return of his investment strategy than Soros's success is for his.
Taleb is correct. If you think he's wrong, you don't understand his argument.
Now, you (and Buffett and Munger) argue that there's an additional reason to believe that Buffett's strategy is a good one: because fewer decisions means that each decision will be smarter. Well, you could be right. Historically, though, human beings are pretty bad at distinguishing good investment strategies from bad ones by logically analyzing their premises. So the statistical evidence Taleb is discussing counts for more, in my book.