I suspect that, to the extent that "Mort!" would act as advertising, my target group would be those people who are not currently transhumanists or cryonicists themselves, but have subculture leanings which reduce their automatic emotional rejection of the ideas: science-fiction fans, skeptics, atheists, and others of that ilk. I don't think I can do anything that would measurably nudge the larger population, who currently resoundingly reject or ignore transhumanist ideas; at least, as you put it, in my own timespan.

As an example, here's a possible use case, at a science fiction convention: Someone drops a Dalek on their foot, and exclaims "Mort!". A nearby conventioneer thinks, "'Merde'?" and asks, "Are you French?" The swearer explains, "No, 'Mort' - death is obscene. Now where's that sonic screwdriver?" The questioning conventioneer and any other bystanders are socially nudged, slightly, in the direction of anti-deathism, and might be a percentage point or so more likely to discover LW in the future; and the swearer has used an expletive to help manage pain. Everyone wins.

I don't think that an anti-deathist swear word is going to make the general population any /less/ interested in cryonics, life-extension, etc.