Even load-balancing multiple servers in a homogenous network, where patches are only deployed in phases is better (and a best practice) than what, to outside observers, appears to have been everything going down due to a mass update everywhere, all at once.
This is where reason gets subjective. If you’re solving for resiliency against a bad patch, then absolutely, do a small test deployment before pushing everywhere. This is a balance that whatever is being patched is less of a risk than the patch itself.
However, look at what is being patched in this case: AV/malware protection. In this case, you’re knowingly leaving large portions of your fleet open to known, documented, and in-the-wild, vulnerabilities. In the past 10 years we’ve seen headlines littered with large organizations being downed by cryptolocker style malware. Only doing a partial deployment of this AV/malware protection means you’re intentionally leaving yourself open to the latest and greatest crytolocker (among other things). This is a balance where the risk of whatever being patched is more of a risk than the patch itself.
Seeing as we’ve only really had this AV/malware scanner problem hit the headlines in the last 10 or 15 years, and cryptolocker/malware nearly monthly for the last 10 to 15 years, it would appear on the surface that pushing the patches immediately actually the better idea.