Because the Chinese mob that thrashed Harry over their lost land deal when the ranchers stood up to the feds and made them back down are feeling heat that people don't believe Harry's excuse for why he's beat up.
So they told Harry to come up with a better cover story for why he's beat up, or they'd beat him up again for not properly covering why he was beat up.
So when Harry's brother got arrested and beat up for arguing with a cop, Harry decided that the fact his brother was beat up would make a good cognitive link with the general idea of Reids getting beat up.
So he used his brother's participation in AA for the cover story of how the information about brother beating brother got out.
So your question really boils down to why doesn't Harry Reid respect the privacy of AA meetings, and the answer is because it didn't really happen in an AA meeting, so he's technically not breaking that privacy, so his brother won't get in trouble for it, because those at the actual AA meeting know it never happened.
And those AA members won't talk about what they know, because Harry's brother told them that if they do, some guys from China staying at a Vegas hotel will drop by to see them.
Clear?
