You could be correct, at least it makes sense.
Do you think he was going to plant the bomb and set it off from a distance?
The other two men that ran, did they also have plans or just to help?
Darn, wish I was a mind reader.....on second thought, no, I will pass on reading minds.
I think this bombing scenario is most similar to London. That means bombs going off almost simultaneously. The "red bus" in London, the first to go, is believed to have "perhaps" occurred prematurely AND THE ONLY ONE NOT IN A TUNNEL.
Just ONE bomb "in the stadium" would result in a stampede AND an opportunity to set off more "at the exit gates". (They would not dare to lock the gates with an in-stadium explosion). When the OU kids' associates heard and/or saw the explosion, they WALKED AWAY in different directions.
I'd look at all the people with backpacks or bulky jackets in the surveillance cameras which are in the vicinity of the stadium near the exit gates "just prior" to the time of the explosion. Wonder what the temperature was? Well, we may not be able to read minds, but if you're a mother like myself, you have eyes in back of your head. :-)