Technically their is a way around it, but it's not really meant to since after that their isn't much to do.
You'll have plenty of decision like that though, this one is just the first scripted one to show what you will be able to choose later on, it's pretty smart.
I quite like both these characters and wish we could have them be companions, I'm still happy with what we got though and it'd be asking a lot to add such a huge amount of stuff on top of what's already in the game.