With the immense trauma the plant was facing, it had no choice but to pull back, but to move effectively, it dropped the demi human.
From part of the absorption of the Vitality, he would more than likely need to be carried back. Though... this created the quandary of what the girls had to do. On one hand, it meant they could carry Randy back with ease, provided Ada lead the way. On the other, it meant they may have to drop some salvage. Either way, the plant was nearing the end of it's life... There was particularly rare flower petals on it's vines it used for arms. 

"Go go go!" Ada cheered in Karn's mind as it rode on her shoulder, it's little arms flailing somewhat.