Today I studied coffee, comparing Black java to Cream/Sugar added.
The results of this study where much more fulfilling than Matousec.
Matousec essentially tests HIPS, unless something has changed since last I checked. And Avast! has no HIPS. So perhaps the better question isn't "Why did Avast! score so low?", but rather "Why is Avast! even in being tested for something it does not have?"