That symbol is wildly insufficient, and the wording of many challenges includes "bonus progress for defeating guardians" but typically PvP is not required for those challenges. It really shouldn't be so hard for them to word things clearly, especially given how VERY frequently this happens. I wonder at what point Bungie might actually start learning from their mistakes...

Thank you! I'd figured it was a wording issue (every other challenge has specified where it is earned) but it wouldn't be the first time something slipped through the cracks regarding challenges so I figured I'd post something about it.