I’m not sure how much of a spoiler she’ll be with 3 votes.
Let's hope you are right. There is no mountain party nominee, so I could see her grabbing 3-4% of the vote.
I don't think it'll be an issue. The Mountain Party usually gets a few percentage points from protest points because 1) they're conveniently on the ballot and 2) they run familiar personalities in the state like Charlotte Pritt and Bob Henry Baber. The Mountain Party would have to actually go out of their way to educate people about writing in Swearengin, and most voters are lazy or already baked-in (and the Mountain Party is resource-strapped anyway). The majority of voters are going to be in a hurry and already have an idea of which of the two well-known candidates they're supporting. I find it hard to imagine many will take the time to write-in an unknown.
Besides, the Mountain Party issued its slate of candidates in June and have remained mum on Swearengin since she announced her write-in adventure despite being active on their social media.