ok, another post on this site made me go back to islam-qa - a site which I am not a fan of, especially since it seems to present itself as such an authoritative place...

The first link was asking about greeting non-muslims and how Muslims should act upon a specific hadith.

The answer was full of bluster and pride about how not to cower etc, but it lacked context, and hence the truth.

So what is the context of this hadith?

It was from a time of war - the Muslims were at war with some tribe and the Sahabahs asked the Prophet something like "we are at war with Tribe X, so saying 'peace be upon you' when meeting them on the streets does not seem to be correct, so what should we do?"