Wow! Free money! Let's go! I wonder if there could be a catch.
I think this is an argument against Norton rather than AV in general. I don't run AV but I wouldn't use this as an argument against them in general. However, I wouldn't go with Norton because of bad experiences years ago: my wife's first OS X Mac was an iBook, with both MS Office and Norton, and it was very unstable. I rebuilt it twice from scratch with no improvement, then did it again but reinstalled things one at a time, waiting a few days each time to see if I could identify the culprit. All was perfect when only Norton was left to reinstall - so I didn't. Not proof but certainly a smoking gun.
This is an argument of AV companies maybe becoming happy to add extra cruft to an already crufty solution. As the sellers are squeezed in a saturated market while companies like Apple and Microsoft improve their own OS security directly they will find adding 'other features' such as crypto a good idea (to their bottom line).
I also got caught by Norton's kernel extension issue many years ago, it's not great their software was adding kernel extensions in the first place and is itself a possible vector to gain access to your Mac.