Bolting to the frame of the house is not the same as bolting to a slab of concrete. It would take about 15 seconds with a chainsaw to cut the wall and free the safe. It would be a lot more work if you had to cut through concrete.
Also I do not think it makes any difference if the safe is in the garage or inside the house. Once the bad guy is inside the garage or the house and can operate without being seen from the outside the only thing that will deter them is the time it take to do what they want to do.
Except in a garage, especially an empty garage, it would be much easier for a thief to wrap a logging chain or cable around the safe and yank it out of your garage floor with his 4x4. Oce the 'safe' is tipped over, its only takes about a minute to break them open. A real safe is mad eout of hardened steel plate, almost all gun 'safes' are nothing more than sheet metal.