Seconded. A great book (I've read 75% of it so far).
About the error you mention - I think you are right - but the author brings up the ~1% because he is talking about 'base rate fallacy' - he wants to say that the errors from the 99% of the population will swamp the true signal from the 1%. So his ~1% number is likely qualitatively ok for what he is using it for. It should still be reworded though - one wants 0 errors in a book about statistics mistakes :)
About the error you mention - I think you are right - but the author brings up the ~1% because he is talking about 'base rate fallacy' - he wants to say that the errors from the 99% of the population will swamp the true signal from the 1%. So his ~1% number is likely qualitatively ok for what he is using it for. It should still be reworded though - one wants 0 errors in a book about statistics mistakes :)