Ban was genuinely confused and concerned about this part.
He was very thankful to the two friends for saving his life back then. Although he was aware that they were trying to leech on him due to the excess energy, he still wanted them to stay and help him in the future.
However, if they can't absorb excess energy anymore due to his core getting fixed, won't that be too bad? That would mean losing two powerful friends that will help him during dangerous moments in exchange for excess Worldly Energy that he doesn't have a use for.
[Host doesn't have to worry. At this moment, the two 'friends' are in a semi-slumber state due to the recoil of forcefully leaving that place ahead of time. They could not even absorb the Worldly Energy for now even if they wanted to.