Yes the SC mods to the car and work done to install the mods could most certainly contribute to a tensioner bolt failing, with the consequential belt shredding and damage to the coolant lines, overheat, etc.
If the failed bolt is proud of the surface, you can weld to it. If not, then you'll probably need to use an EZ Out. Even though you say your dealer is mod friendly, I would not take this to a Chevy dealer to repair. Best case you have someone inexperienced with these kinds of mods trying to fix it. Worst case you lose the drivetrain warranty. I'd take it back to the shop that did the mods in the first place (Lamar Walden?) and ask them to fix it. I'm sure they've had to deal with a broken bolt or two before
