Would They Pose A Risk of Violence?

There was a message on my home answering machine requesting a return call. A former co-worker gave my name as a reference for a job. The company requesting a reference is a national retail chain. The message had a sense of urgency.

Please return my call regarding X. I need you to answer 3 questions before X can be considered as an applicant for a job.

I did not want to hold up my former co-worker's job application. I called the human resource person and was quickly asked 3 questions. The questions were not what I anticipated. I was expecting basic employment information.

The Questions:
Question 1: In your opinion, would the applicant pose a risk of violence?
Question 2: Similar to question 1 but I cannot recall the wording
Question 3: Do you know of anything that would prohibit the applicant from doing the job?

The human resource person thanked me and ended the call. This is not the first time I was a job reference but it was the first time I was asked about the potential risk of violence.

OSHA defines workplace violence:

Workplace violence is violence or the threat of violence against workers. It can occur at or outside the workplace and can range from threats and verbal abuse to physical assaults and homicide, one of the leading causes of job-related deaths. However it manifests itself, workplace violence is a growing concern for employers and employees nationwide.

I answered the questions about my former co-worker. Then I began to over-analyze the phone call. I am responsible for interviewing applicants for seasonal positions at my employer. I am not a human resourse professional but I do know there are questions you cannot ask during the interview process.

Should businesses ask opinion questions about violence during the application process? Should I have answered the question? Is the workplace being cautious? Are they protecting themselves against a negligent hiring lawsuit?