Stop a country because 6 people died in a train accident?
I'm sorry, that's unfortunate, but a lot more than 6 people die on car accidents every day, so should we stop every country every day?
I don't see how stopping a tennis tournament honors people who died in a train accident. I don't see any connection...
We're a country of somewhat more than 4 million people and not exactly the size of Russia. Things like that don't happen often, let alone daily. Besides, not everything stops working, it's more a sign of respect for the victims. Obviously, they assessed they can organize the tournament well regardless and the off day presumably gives an opportunity to potential spectators that will attend the memorials to come another day.