The way Frisk sees it, nothing that happens down here can be significantly worse than what happened in the last lab they visited. As long as Sans is still himself, that's all they ask.

As the flowers release them to turn on the scientists instead, they slide down off of Lion's back to look around. Yeah, they can imagine what these tools are for. Doing things like that on purpose...what terrible scientists. The vines still remind them of Flowey, for all that they watched Mr. Universe move them himself, so they're very careful in stepping around and over them, circumnavigating the scientists to go investigate whatever that one dropped. Video game rules - it's theirs now.