IDP/behavior shield has no protection against petya.
You tested petya too soon
so avast failed quite early
I perfomed a similar test and left petya at the end of the video and obviously it couldn't protect
someone posted my avast IDP video on avast forum and they smashed me because I disabled the other modules, the test was invalid, not a bypassed, those 3 modules had a link to each other and should not be disabled... bla bla bla