Thanks, that was very useful advice. I got to Relevance clause 3:
(name of operating system as lowercase contains "win" and version of operating system >= "6.0" and version of operating system < "6.4" ) )
All of my endpoints, including the relay I’m deploying to, are Win 10 or Win Server 2016, and so the version number is 10.0.x and this relevance evaluates to false.
I created a new copy of the deployment task 801 and edited that relevance clause to allow Win 10 / 2016 installs. My 9.5.10 relay now shows up as an applicable computer. So my follow up question is: What’s the risk if I go ahead and deploy the vCenter management extender to a Windows 2016 relay?