But it still portrays snakes as Satan, and isn't Satan supposed to be evil, according to Christians? So, yes, it does 'say' that snakes are evil.
And just because 'several different animals' are used to represent Satan, doesn't mean that's its any less harmful to snakes as a species.
Do you ever hear people say 'Lions should be killed because they are sinful and disgusting creatures'?. If anything lions are seen as majestic and beautiful animals that are meant to be respected, so bringing them up makes no sense.