My trying to increase the probability by multiplying by 10 billions proves suggests that I have no idea how the numbers evolved here.  Evidence of a proposition is not the same as a proof of that proposition within a model.

In fact, I admitted that I only skimmed your calculations, and I'll further admit that throwing in all humans as workers was a sorta off the shoulder comment made without consideration of the specificity of your calculations.  I'm focusing on the categorical difference between impossibility and improbability.

If your argument is basically this:  X is improbable. 
And my reply is this: X is improbable doesn't imply X is impossible. 
And your reply is this: no, X is very very improbable. 
Then it seems like we're talking past each other.

You said you like semantics.  So do I!  Perhaps we can find some agreement here:

1) An event with probability > 0 is not impossible.
2) A proposition supported only by inductive evidence is not deductively proven.

Cheers!

Calculating something is also being sure your result is right. And that is precisely impossible.