The bottom bracket shell is thicker than the tubing that's welded to it, so your chance of breaking your frame in this area is extremely remote. However, if it did break, you certainly would have a case for warranty replacement as the cable guide was original factory spec and the company's product engineers
should have made sure that gear cables would clear the frame.

A couple of the other posts in this thread have good, simple solutions to solve your cable clearance problem without major expense and trouble.

By the way, great photo!