Answer:
It suggests something mean and angry.
Step-by-step explanation:
Just from the sentence provided and the main definition of "snarled" we are able to infer that the best reasoning for his use of this word is because of the negative connotation that the word has. So because snarled loosely means to speak angrily or aggressively it is safe to assume that that is the type of mood the author was aiming for.