Shelley's solution can be seen most clearly in stanzas 6 (specifically line 24, "Forge arms--in your defense to bear") and 8 (which urges them to defend themselves unto death).
My opinion: I think that he is using sarcasm in terms to identity the problem and what will happen in their future if they continue down the road they are going. I do not agree with him if he is not being sarcastic but I do agree with him if he is. I don't believe avoiding problems is ever beneficial.