So Kaguya comes back and sees two people with SO6P chakra, probably the two strongest living people other than herself on the same continent as her. she realizes they could be dangerous and decides to deal with them. Even though they have SO6P chakra she's obviously got a massive edge here considering she's got the tree + juubi and knows how to use them.
Now to my point : How many methods of flight have we seen in this manga. so many characters have one form of flight or another at this point. and no one even batted an eye when madara and obito started floating around with no explanation as to how. hell in part 1 sasuke was flying around the trees with his stringy things.
It's not clear whether she teleported them or created the lava right there but seriously, why not either
1. teleport them into the lava
2. create the lava around them instead of far below them
3. atomize them instantly since there's absolutely nothing protecting them from her simply obliterating them
instead of lazily putting them into a situation most shinobi could escape
