Regardless of what sport you're playing, if you get knocked out the worst thing that can happen is that you get K/O'd again, your brain swells, and you die. That's why it's important to stop play for a while. Seeing Bell hit the deck in the main again was really concerning for me.
I understand that all TBIs are different. I also learned a lot last year when I took a dirt nap for a couple of minutes at Chilitown. I could have ridden again in 15 minutes, but not well. I had trouble concentrating for about a month afterwards, and it was really a bad situation. TBIs are pretty serious stuff, but kids don't realize that. In my opinion, K/O'd or not, Bell probably had a concussion from one or both of those impacts and it was probably in his best interest to sit the round out, regardless of what the Asterisk folks said.
Also, per the 6D helmet release, I guess the new tech is supposed to help mainly in low velocity impacts, not so much high velocity stuff. Not sure how much the helmet helped in his case.