oh man! I hope that does not happen to the rest of us that have one of these..
Been down this road before with an old Apten lower setup with a tiny idler pulley that I couldn't source when it failed and had to buy a Metco setup. I've since switched to a caged 6lb and bought an extra idler pulley for that very reason during the GB.
If you locktited the bolt you'll be fine as far as it backing out. If the chinese bearings seize and shear it off, there's nothing you can do. I pulled said bearings out and replaced with ceramic$ before installation .
With that said the 6lb spins the supplied idler to 27k rpm at the motor's rpm limiter. 27k rpm is above the rating of even the ceramic$; however, the supplier has never seen a failure and said to be more concerned about lateral failure from an overtightened belt.
You can reach me via PM if you'd like ceramic bearing info.