It's because men are more likely to use a gun to commit suicide while, for whatever reason, women are more likely to down a bottle of whatever there is in the medicine cabinet that they think will do the job. This ladder approach backfires if you dont know whether a specific medicine is designed to induce vomitting in large doses or how to negate that concern (and with suicide being tied heavily to moments of impulsiveness, by the time you finish the research your resolve may have left you)