MAO-B and A inhibitors (they inhibit the enzymes that break down dopamine, serotonin and other amines) are not too uncommon to be used as nootropics in the nootropic communities, and selegiline has probably some more nootropic effects. It is also used for ADHD. While definitely indication of risky behaviour (disrupting body's homeostatic and allostatic mechanisms is quite risky, people can die when taking this together with foods high in tyrosine) I doubt he used it specifically to increase impulsivity.