> Whatever happened to rather that 10 guilty men walk free rather than that one man be jailed innocent?

That has always been bullshit, the way you and most of the Internet are misusing this quotation.

Why 10 to 1? Why not 1 to 1 or 1e100000 to 1?

This ratio is purely arbitrary.

Obviously, if you really followed through with the gist of your argument, we should never convict anyone, because better to let everyone go than miss the one injustice in a thousand years.

Unless you can make a case for a specific ratio, 10 to 1 has no special meaning.

The quotation only argues that the balance should be biased towards aquittal. Nothing more.