The term 'rat' for a traitor/snitch is unfair to rats.

I am not being snarky in a mean way to people like Snowden or some dude/chick who ditches a gang for justice and/or their own wellbeing.

I am telling you that rats are some of the most gang-oriented creatures out there. The rat is deeply loyal and concerned with the wellbeing of their fellow mischief (group of rats) members.

Rats are only violent for three reasons; food, sex and gang/tribal alienation. They take time to ever be truly kind and interactive with others and this includes their human owners. Rats can recognise smells very well and know their regular human feeder or even neighbour of they're wild and being fed now and again.

Unlike racoons or cats, when you feed feral rats they understand that your relationship is only a win-win temporary interaction. They only get cuddly and stuff if they are rather extroverted and sense you keep reaching out to do so. They comprehend social nuance very well and have a depth between best friend to stranger that is so intricate that they are one of the few creatures to successfully maintain social order despite being polyamorous. Sometimes there are brutal fights over jealousy, regarding the polyamory but there is a clever reason why the females are proud nymphos; the male rats never fully know which of the dudes that banged her are the father, leading to all pf the ones that did then protecting the offspring.

I agree, they should be called Judas. Take the aforementioned Judas. Without quoting chapter and verse, the CliffsNotes of Judas’ snitchery go like this: Judas was Jesus’ buddy, a disciple, and at the Last Supper with Jesus and the other disciples, Jesus predicted that someone there would betray him. After dinner, Judas ran to the Roman authorities, who wanted Jesus for religious fanaticism. The Romans gave Judas 30 silver coins in exchange for him telling them where Jesus would be tomorrow. The next day, Judas lead the Romans to Jesus, Jesus was arrested and — spoiler alert for a 2,000-year-old story — later crucified (don’t worry, he got better). 

I've always liked the word FINK which can be used in all the same contexts or even in combination with RAT.

The second part of your post is the entire problem.

Many predators of rats are much more treacherous and scumbag-like to those they could choose to be loyal to.

These include feral cats, snakes and weasels.

I mean, you could argue that humans are the same, we just take the third one entirely too far.

A baby rat born from unmarried adult rats is a rat bastard.