A gun is an inanimate object. Criminal law applies to criminal behavior on the part of human beings. Therefore, your argument is nonsensical.
A gun kills. Speech does not, especially when you choose to kill yourself.
By making this creature responsible, you are saying that people have no free choice. The government will make us responsible for another persons behavior.
This trend is already starting, like the attempts by the Democrats to make gun makers liable for gun violence.
Speech is exhaled air and vocal cords. It does not kill unless acted on.
Look at the bullying prosecutions on Facebook. A girl kills herself because of Facebook bullying, and they want to make that criminal.