No, it is not. That's one of those great myths of the Canadian firearm debate, that if they don't have a gun, they'll find another way. We hear that time and time again. The truth is that it's simply not true. Of those who have survived a suicide attempt, only 10% of those remaining survivors will actually complete suicide.
Suicide is an impulsive act. Yes, there are some people who plan it meticulously and have plan A and plan B and plan C, but for the great majority of people who commit suicide or attempt suicide, it's an impulsive act during a time of feeling overwhelmed. If you can get them through their depressive episode, their suicidal episode, their psychotic episode, then chances are very, very good that they will not go on to suicide.
That's a myth that needs to be debunked.