Live Response in Microsoft Defender for Endpoint is a powerful investigative and remediation capability that lets responders interactively run commands on an endpoint, collect files, and perform remediation steps (collect investigation packages, pull files, run scripts, or take forensic artifacts). However, Live Response is an on-demand tool invoked during or after an investigation; it does not by itself provide continuous detection coverage or automatic blocking of artifacts that a third-party AV missed. The requirement is to ensure devices are protected from malicious artifacts that were undetected by the third-party antivirus. To meet that objective you need capabilities that detect and block artifacts automatically (for example, EDR in block mode which actively blocks/remediates post-breach artifacts even when Defender AV is passive). Live Response helps respond to an identified artifact but does not create the detection and automatic blocking coverage that prevents or remediate undetected malicious artifacts at scale. Therefore enabling Live Response alone does not meet the stated protection goal.