Not much reason to think they could survive the side effects when it wears off. ”Just because Zoro can” isn’t much of a reason.
Really the medicine should be going to people like Jinbei, who have taken a bit of damage but nothing seriously. Giving it to be people who have had an extreme diff like Zoro is a massive gamble on what happens to them afterwards. Only Luffy and Zoro have shown the extraordinary willpower and strength to show they could survive something like that (Mihawk’s wounds, Zoro taking Luffy’s pain, Ivankov’s treatment etc).
Really the medicine should be going to people like Jinbei, who have taken a bit of damage but nothing seriously. Giving it to be people who have had an extreme diff like Zoro is a massive gamble on what happens to them afterwards. Only Luffy and Zoro have shown the extraordinary willpower and strength to show they could survive something like that (Mihawk’s wounds, Zoro taking Luffy’s pain, Ivankov’s treatment etc).