Norton 7.1 Build 94 for Apple Mac and Safari Extension in Safari Version 9.1.2 (11601.7.7)

Norton 360 for Mac
1

I am using Safari Version 9.1.2 (11601.7.7) on Mac El Capitan 10.11.6. There no Norton Extension installed in Safari actually. However, another two browser on my Mac Google Chrome Version 52.0.2743.82 (64-bit) and Firefox ESR 38.5.2 both have Norton Extension installed.

Norton 7.1 Build 94 -> Advanced -> SafeWeb -> Safari is green checked as Protected.

Is it not more necessary for Safari to install Norton Extension with Norton 7.1  Build 94 for protection?