The more I watch the clip, the more I kind of side with thinking the fight should've continued.
Reem was immediately back on his feet. And although he was extremely hurt, he wasn't completely KO'd. A fighter shouldn't be allowed to call his own shot. Meaning, even if you know that man is extremely injured, you don't stop until the ref stops it. You don't walk away because you deem it fair or necessary.
Some of you call it sadistic, but that's combat sports. Hell that sports in general. Where my football players at? What did your coach tell you? You play until the ref blows the whistle! Linemen, you drive your opponent into the stands until you hear that whistle.
Let's change the scenario slightly. Let's say ol dude hit Reem, walked away Mark Hunt style, and Dan DIDN'T step in?
Personally I'd rather a fight finish like Romero vs Rockhold, then the way that fight ended on Saturday night. At least I knew Luke wasn't getting up and he was completely KO'd Reem was back on his feet and with 4 seconds left, that must suck.