I would never trust a lock that had a blow torch used to free up components. There would be distortion on the components and damage to other parts.
The only exception would be a lock frozen with ice. Even then, I’d try using a de-icer spray or would try heating the key. A hair dryer would be the most heat I’d prefer to use on the lock itself.
That’s my non-professional opinion. Your mileage may vary.
Gordon