I think he wants just to limit the animation to when it is scanning specific items. The problem is that AVAST is always scanning, it is not random, you're getting all sorts of cookies and other crap sent to and from your PC all the time which AVAST needs to scan to be able to block. That is pretty much the point of it.
Personally I hate anything animated in my task bar/system tray and about the only thing I tolerate is a CPU temperature monitor and system monitor both of which are unobtrusive and actually useful. AVAST's rotating icon tells you nothing except that it is doing something. I do not need to or want to know that, it is either doing the job it is there for in the way I want or it isn't. The animation is just unnecessary decoration which may either comfort or worry the paranoid. Not sure which, me it just annoys.
As Asyn describes AVAST thankfully provides the option to disabled the animation.