How does something "concealed" constitute a "clear" threat?
Because he's ignored instruction and is reaching for something out of sight. If his intentions are certainly safe, he wouldn't be ignoring instructions, especially with a gun aimed at him.
Look at that scenario and tell me what he's more likely to be reaching for - a gun or a dropped chocolate bar ffs.
Once he ignores instructions and reaches into a concealed area, he's a clear threat.

