I admit that that comment was flippant, but you’ll note that I said “apparently” there. I admit that Ibrahim Biari’s death has still not been confirmed, although I’m also unaware of any strong evidence that he is still alive.
With that said, I do think that Israel’s claim is less difficult to believe. It wouldn’t be surprising that a specific person Israel wants dead would be among the many people killed in that bombing, whereas it would be surprising if Israeli soldiers executed a group of women and children, at least because doing that would be absolutely terrible for Israel’s international relations. Even countries which accept that civilians will be killed by bombing aren’t going to support deliberate murder.
I’m not saying it’s impossible. Soldiers do things like that sometimes. I am saying it’s unlikely enough that commondreams.org shouldn’t be publishing what is effectively still just a rumor.