Radiator Replacement Small leak of transmission fluid

Small leak of transmission fluid where the transmission hose connects to the radiator.
Mechanic states that radiator must be replaced (radiator is free of charge, as it is under warranty), but labor is about 5.5 hours.

The connection is part of the radiator, and cannot be removed.

1. Can a sealant (silicone?) Be used to seal the leak?

2. Would that cancel the warranty if radiator needs to be replaced down the road?


Thanks.