..........I would say, your house, your rules. If you feel more comfortable having them locked away (rather than muzzled) then so be it.
Absolutely true about your house and your dogs! You have to do what you think is best.
Some folks are too fearful of GSD's and some seem to be just the opposite.
We recently had some work done to the house and the guys wife happened to come along while he was finishing up one day. She had a 9/10 mo baby with her. And we had Baron in the back yard when they arrived. So he greets them and is his usual friendly self and before I even noticed what she was doing she holds her baby down so Baron (then about 2 yo male GSD) could get a good sniff! That was bad enough but after she and I were sitting on the patio waiting for her husband to finish up, without saying a word she puts the baby on the ground and lets her crawl around. Now Baron is loose and sitting right there! He had never seen a baby that small nor of course been around one. I was stunned that she would do this with an adult GSD that she had never met before!
It turns out that he was really cute with the little one - going over and gently sniffing the little one.
But .........
I would expect any normal adult GSD to be good with kids generally, but I would not let them loose around the real little ones that they could hurt just by bumping or even stepping on them.