Barry while the calculation might be correct (am to lazy, read inept to check it) the conclusion is wrong.
Just because the odds are low doesn't mean it won't happen. I could win the lottery while the odds state I probably shouldn't win if I buy a 100 lottery tickets each drawing for the next 50 years. Yet there is a chance I will win it on my next ticket.
Conclusion; just because the odds are low it does't mean it won't/can't happen. Therefor your entire argument is void and kind off pointless...
... though writing this down amused for me about a minute so not entirely pointless I guess. ;p