There's going to be some nuances to "yuri" due to the term becoming popularized by more ecchi and explicit media, but I think it's practical to treat the modern use (post Sailor Moon) as related to works and aesthetic that is "lesbian" or "saphic". That's denotation but has a giant loophole. Art is ludicrously broad and unless your language has an academy dictating word meanings, genres can be very loosely defined. It's easier to treat everyone's definition as correct if they overlap enough, so, like how most words develop connotation.
It's fair that the author considered an interaction a running gag but not saphic enough
at a publishing and sales level because there's no "preciousness" of emotional content. So the author demonstrated a view of yuri that would've been mocked in online spaces in the past, but it's kinda flattering in an odd way? If persistent ecchi titilation isn't yuri to them, they're oddly transcendent using evolved language and inattentive to how publishers and art sites label it. In a way their definition as an artist and producer in a market economy was wrong, but it's a pretty sensible and kinda respectful definition used by a consumer who isn't all that mindful of lesbians but understands queer vibes matter to the community. They didn't think of it as a genre to honestly attach to their work, publishers saw an audience, no harm no foul.
More cynically, the author didn't make the scifi stand out enough, nor the slice of life, so what was most salient for putting the book on shelves for reader type was that it's lewd often. Yuri by process of elimination. That's the biggest divider for audience attention because the story ain't literature, and even dense SF that has yuri has strong pull to be placed in yuri sales categories. Ghost in the Shell and some western SF with lesbian protagonists don't spend this much time on saphic teases. Unless queer interactions is a background element, like implied but not repeatedly physical or focal in ways that may wind up audience, publishers silo it off to queer genre shelves (if publishers even distribute it).
Word havoc gets worse since it's genre and aesthetic, and creatives can go gonzo with that. We give abstract concepts arbitrary boundaries to ignore the extremes. Enough teases can also be yuri. Two curvy rocks leaning on each other...
two bottles in a meme...
a wistful fan gazing at an empty bench... this too is yuri. Maybe. Not all rocks, bottles, and benches. The only territory to actively rule out is outright queerbaiting, but that too is post-hoc reclassification.
And this series isn't queerbaiting. It's soft porn. Historically yuri.
