Why is it important to call assistance if guest is not cooperative?

It buys you time and provides a second outlet for the problem guest.

Explanation:

Often when a professional encounters a non-cooperative guest, he or she must employ strategies that control the troubled guest and maintain the safety of the professional and other guests. The best strategy in this case is to call for assistance. With the assistance the professional can take time to try to solve the problem of the host, and can offer a second exit so that the host becomes cooperative and no longer causes problems.

For safety of yourself and the guest.

Explanation:

You never know what might happen, so it is good to get witnesses, as well as multiple inputs on a certain situation.