Hi eric,
No - BNS's dividend is quite safe. Remember that the dividend ranking is a combination of multiple factors including dividend growth and safety - not just yield. One of the reasons why TD ranks higher than BNS because it has a much higher historical growth rate and because it has a lower payout ratio.
If your main goal is higher dividends, then BNS could certainly be a viable option. We don't advocate focusing on yield only and beleive that total returns (share price appreciation + dividend) is a better indicator, but we also recognize that there are many reasons why one would focus primarily on yield. So with that in mind, no BNS' dividend is not at risk - remember they just raised it by 10% last week and would not have done so if it was in danger. Canada's banks have the best dividend track record in the country.
Mat