Image from OP with added ALT text. I've redacted the names in the e-mail screenshot, as they aren't important to the gist of the e-mail.

Here's a clearer version of the pictures that the screenshot tweet refers to with alt text. It appears to be unclassified chat history. Highlighted sections are also noted in the alt text.

This list isn't a list of people who support RFK jr, it's a list of people Nicole Shanahan threatened with contributing toward their primary opponents if they don't vote yes for RFK jr. This context - minus naming the billionaire - is in the omitted first line of the post you screenshot.