There is one point I should stress, though - the anti-virus is not letting me to disable its self-defence mode. If it did, there wouldn't be a problem - I am quite aware of that registry entry you mentioned.
As far as i understand, this Business Antivirus relies on configuration via Cloud web interface, and I am unable to find an option to disable self-protection there.
The cloud interface just applies
some settings to the clients periodically. Meaning if a client setting is changed and that setting is managed under cloud, then every so often (I think every 10 minutes) the setting from the cloud is reapplied and always rules. As far as I know, there is no setting for Self-Defense Module on the cloud, so the client setting always rules. The available cloud settings grows as the client application develops over time.
The Password Protect option in the cloud would be your strongest defense against having the client have any changes allowed.
So it is therefore interesting you can't disable Self-Defense Module, as an admin should be able to if you have no cloud password settings applied. I admit I've never tired to disable it on
server. Are you logging onto the console as administrator ? (ie mstsc /console) Maybe you can't do it as a regular user session on TS, since it attempts to display an "are you sure" timed dialog box, presumably only on the console session.
At the topic of being not targeted at terminal services installation - well, since the product is said to support Windows Server environment, it sort of implies any general server use, either file server or a terminal server. This is my opinion of course.
Absolutely, don't get me wrong I'm not saying it won't work
I'm just pretty sure Terminal Server isn't
specifically in mind when developing this multi-platform product as Avast might for other products designed for Server. If they did, they'd make it easier to hide the system tray icon
It's possible you found an uncommon bug that you can't disable self-defense when there are multiple AvastGUI.exe running like on a TS. Touch base with Avast support if you can on this matter.
Anyway if I can find a moment I'll spin up a VM and see if I can replicate your experience. I wonder if Group Policy could delete the registry key somehow...