Yeah, under that definition it’s not a spoiler.
Personally, when screening for Minda and encountering this kind of gray area, I kinda tend to lay weight on what makes for the best experience, both for Minda and the audience, though there’s no clear catchall rule.
Ultimately, I’m leaving it up to Sharks to decide where the boundaries lie and what constitutes a spoiler. After all, I can only speak as someone who’s not read the entire story, which is the whole point. I can’t be asked if I consider something a spoiler without that thing being told to me (which is what happened in this case), and once it’s been told to me, I still have a limited perspective on how spoilery or non-spoilery it actually is.
As a starting point, though, I guess I’ll say that anything storywise that I couldn’t/wouldn’t reasonably figure out if I were reading serially at the time of the latest chapter’s release (ignoring the fact that I’d be 14 at my current point in the story), or rereading with my current knowledge in mind, is a spoiler. Word of God might be an exception to that, but that’s up to Sharks.
(And no, the scentless man is not covered by that definition either.)