Grapefruit is an enzyme inhibitor that blocks clearance of many pharmaceuticals. That’s dangerous as it can lead to accidental overdoses despite taking the right dosage.
The person here ‘being themselves’ needs a 'script to deal with modern society and can’t have grapefruit as a result.
I’m not following your question… Grapefruit inhibits the breakdown of meds, it’s probably important to appropriately dose HRTs over days/weeks or else there could be some problems with the endocrine systems due to unexpectedly elevated levels (e.g. cardio stuff).