Actually, I think a CVn is arguing rather strongly for the sci-fi tag. Sometimes a question can be answered, slightly differently, given the genre bias of the respondent. If the querent is making a "sci-fi" universe and specifies that answers should be "sci-fi" oriented, based on the tag, then I as respondent would know to leave out the quirky, fantastic aspect of answering. In other words, the setting is important to the answer!
As far as searching for questions goes, I'd be much more likely to search in general terms for "sci-fi" than something specific like "transporters". Unless I were looking specifically for queries with that particular search term.
For queries tagged SCI-FI, I would be expecting queries about worlds and settings similar to Star Trek or Babylon 5 or Battle Star Galactica: space ships, laser guns, transporters, matter replication, space travel and the like. In conjunction with the spectrum of science tags, I'd expect a lot of primary world physics and mathematics to come into play. Even with other tags present, I'd still be expecting queries and responses aligned with that genre.
I would not expect much in the way of magic or mythical beasts or where to find them or how to deal with the wonkiness of a wonderworld. Here, in conjunction with the various science tags, I'd expect a much more creative (and "opinion based") application of alternate and altered sciences. I would not be expecting queries aligned with fantasy, mythological, alt-historical, steam- / stone- / mage- / bronze- / etc-punk genres. Nor even necessarily futuristic fantasy-scifi settings.