so far it seams like the triggers are high utilization and abnormal charges was anyone who was closed by citi had a citi checking and if so did thy make some abnormal deposits as well (maybe when thy know you regular spending/deposits thy get more suspicious)
As the saying goes, don't **** where you eat.
If it wasn't clear until now, it's now painfully obvious that you don't bank where you have your CC's.
Operation choke point is targeting bank accounts, and in general that's where most of the regulatory focus is. With Chase you're severely increasing your CC shutdown risk if you play with your bank account, and with Citi it seems that that having a checking account with them was a condition for shutdown scrutiny.
I personally have a MS checking account at a bank that doesn't have any CC's I wouldn't be embarrasses to carry.