Regrettably this behavior appears to be protected by the first amendment, unless suicide itself is made illegal (as it used to be in many jurisdictions). A law criminalizing such behavior in Minnesota was reversed at appeal: http://blogs.wsj.com/law/2014/03/19/encouraging-suicide-isnt... and http://en.wikipedia.org/wiki/William_Francis_Melchert-Dinkel
I can't politely express my opinion about people like this.