Should indoor ripened tomatoes be used for sauce?
I've never heard that. I have picked end of season tomatoes when they were green and let them ripen and used them for any purpose that I would normally use ripe tomatoes. And I know others who do also. It's much better than losing them to a frost or to animals.

If there is any downside, it would be that they might not be as flavorful as vine-ripened, but that still beats losing them.

Also consider that most of what we get in grocery stores come from large farms where they are picked green. 

Just for the sake of saying it, many stores now also sell vine-ripened or locally grown tomatoes but they do cost more.