He eventually brings it back. Around 20 minutes in he revisits mitochondrial DNA and electrochemistry. This type of stuff is very interesting. Chemistry is all systemic balance and people tend to forget that some universal rules are still true. Fluorine is too volatile of an element to put near living things by choice. Every time we try to use it we end up with issues. Sometimes the volatility serves a purpose, like rapid delivery, but generally the juice ain't worth the squeeze.