Sparkly,
First of all, I said “if you assume smartphones are assur…”
I never said they are assur, but there are those who say that they are.
Secondly, smoking is not pikuach nefesh. If it were pikuach nefesh then it would be permissible for one to be mechalel shabbos in order to stop another person from smoking. Since we all know that it is not permissible to do so, the logical deduction is that smoking is not pikuach nefesh. QED