Earlier quoted context omitted.
An updated version of that section in the form of a booklet was distributed to every household a few years ago, the advice is mostly the same. Stay Alert! Trust no one! Keep your laser handy! (OK, that last one came from somewhere else).
“Trust no one” is not what the newer or the older version of the pamphlet suggests, rather it quite correctly points out that during wartime the amount of misinformation can be expected to be massive, so you should be extra vigilant in verifying the source of the information. Trusting “no one” would imply a complete free-for-all which is hardly conducive to an effective defensive strategy.
Which is exactly why RT and its American (and other) repeaters are so insiduous.