Maybe they shared the cigarette because they didn't have many. I don't think they had pot in that part of the world, it's just a North and South American thing, but it could be shipped over there. A lot of people today would be surprised to find out that not only was smoking common and accepted back then, most drugs that are illegal today weren't then. It's said that the founding fathers of the US, including Washington and Jefferson, not only smoked pot but grew their own. It is supposed to be what was in the Native Americans' peace pipe. Marijuana was not made illegal in the US until the late 1930's after the movie 'reefer madness' caused an uproar.
Cocaine was legal, too, and yes, Coca Cola got its name because when it began in the 1880's it had a little cocaine in it. I saw a quote from Nicholas's diary once about cocaine, saying something like 'this is good stuff, everyone should use a little every day'

So perhaps some of his bad judgement was drug induced. Not judging them though.