I would hate to vote someone out on a 50/50 shot...but if it must be done, and they are willing, the greater good must be taken into account. I also just want to mention that we are taking Brewers word as pure fact here. Is there any possibility that this story is somehow a fabrication regardless of how elaborate it is?
It's absolutely a possibility. The reason most are taking it more seriously is not only because it's elaborate, but because he's not gaining much if he is making it up. At worst, we would spend two days lynching AbT and MK, only to realize that both of them were town the whole time, which would basically guarantee that brewers gets lynched next. With 16 players still alive, there's just no reason for him to put himself in that position right now.
Also, I know you're new, but one thing to get used to is that votes are very rarely sure things in mafia. 50/50 is pretty good odds, especially this early in the game. Usually you'll either be very unsure who to vote for because there's no way to tell who's story is real and who's is made up, or even if you get to 50/50 odds, it's not until the end of the game where being wrong means you lose. Right now there's relatively low risk to being wrong (there is some, mainly that one of the two is an important town PR like cop or doctor, but it's not likely with so many still alive), and having a good chance to get scum with our first kill is a huge advantage for town.
TL;DR: Don't trust anyone 100%, but don't wait until you're 100% sure you're right because you'll be waiting all game lol.