xpinstall.signatures.required is true in about:config on my Firefox. It seems like that doesn't matter. The only other add-ons I have are NoScript, Pocket and L

xpinstall.signatures.required is true in about:config on my Firefox. It seems like that doesn't matter. The only other add-ons I have are NoScript, Pocket and LastPass and I trust these. The McAfee add-on only has a "Disable" button and when I disable and restart, it does get disabled. I am unable to remove it and the external McAfee installer/configuration manager does not have any settings to prevent it from getting installed. And every-time McAfee updates itself, it re-enables it's add-on and I have to go in and manually disable it. I am surprised that no-one else is facing the same problem and is not complaining about it (Google search didn't show me any results regarding this topic and I found only mentions of similar problems (pre 2014) on the Mozilla forums).