@sj
There's a huge gulf between what Sarah is saying and your "Firefox turns into a keylogger" or Lunduke's "can use your data however it wants".
The "use" in the TOS is limited by the privacy policy which Sarah says right in that thread. Her complaint is the privacy policy is overly broad and vague and that's a perfectly fair thing to argue about (I have my own questions about what it means). But that's very different from "however [Mozilla] wants"
A "keylogger" is malware and a crime, and the accusation is offensive. You better have something stronger than a truncated sentence from the TOS to make that claim.