Do you have a source for the first assertion? I can't find any studies on google.
I'm skeptical because people so often attribute many of the negative effects of other chemicals in tobacco to nicotine with no evidence (a point the OP hammers home at https://www.gwern.net/Nicotine). Even the FDA seems comfortable with this conflation, as evidenced by their disposition toward e-cigs.
It would be pretty hard to separate the effects of nicotine from the effects of a lifetime of smoking + potentially poor dental hygiene (gum disease is rampant https://www.perio.org/consumer/cdc-study.htm) + aging.
Per wikipedia (https://en.wikipedia.org/wiki/Nicotine) the general medical consensus is that nicotine poses few risks on its own for nonpregnant adults, besides vasoconstriction and dependence.
I'm skeptical because people so often attribute many of the negative effects of other chemicals in tobacco to nicotine with no evidence (a point the OP hammers home at https://www.gwern.net/Nicotine). Even the FDA seems comfortable with this conflation, as evidenced by their disposition toward e-cigs.