What is the outcome of the NSDAP's visit, and why would Max be clenching scissors?

The Nazi party is measuring basements to see if they would make good bomb shelters. Liesel causes injury to herself playing soccer so she can warn her family. Before they get a chance to move Max, the Nazis are at the door. Max was hiding under drop cloths and clenching scissors in case he was discovered. The Nazis didn't see him.