If that were the case, one could also make the argument that any of the physical statistical profile fields were also a form of Eugenics – specifically, things like body type, race, height, eye color, etc.
Unless you have access to an amazing new site (tell me, I'll sign up!), there are no dating sites currently which use their matching algorithms to force a mating that produces offspring. This would seem to be a pragmatic requirement of any successful Eugenics program.
It is possible that, if enough credence were given to a given dating site's algorithm as being actually effective in producing accurate and successful longterm matches that would lead to offspring, and enough people worldwide joined as a result (numbering in the billions), that this would create a "defacto" Eugenics application – assuming that the site used at least some genetically-influenced characteristics for its matching, and further favored certain types of matches across races/cultures/etc worldwide. Data from 23andMe could then also be used to accelerate the speed of eugenic effects after the first few generations of offspring.
As someone working on an online dating site, I find the prospect to be a highly unlikely outcome within our lifetimes, either intentionally or accidentally.
Would a dating site that used 23andMe data be considered Eugenics?