... pure gold and has been vetted by many industry professionals ...
From that same organization, there is also a list of Security Guidelines for Congressional Campaigns (april 2019).
Here are a few quotes from that document:
Uninstall all anti-virus software. ... The only exception is Windows Defender.
You must use an iPhone, model 6 or later. Android phones are not safe to use.
Use Google Chrome as your default browser on your laptop. ... Avoid Safari and Firefox
These seem like some pretty strong claims.
Unfortunately, no references are provided.
I've spent some time trying to find information that supports these claims, but what I've found seems either, old, inconclusive, or opinionated. For example, there's an interesting discussion about iPhone and Android phones here, but this does not deal with stock android. This discusses how antivirus software cannot protect against all threats, but doesn't say not to use any, and this explains how it is difficult to compare browser security.
Are the above guidelines all just opinionated, or does any consensus exist (among security experts) on these subjects?
Note, I'm asking for facts that either support or oppose these claims.