That is actually likely to be a valuable bit of demographic data. It's one of the rare pieces of information that indicates altruism, along with charitable giving. Many advertisers would like to be able to target organ donors.
In Canada it also apparently used to potentially say something about your sexual orientation as well, at least if you were male - gay men were barred from donating organs a few years ago.
That is the case in many countryis with blood. The Danish blood bank ran into an issue a few years ago where they warned of a possible blood shortage a few years ago and they then turned down blood from (healthy) male gays.
You can't donate if you had sex with a single male 30 years ago, but I can sleep with all the females I want and still donate.