Indoor Tethering? Other Options?

Pretty much no matter what you choose, there are risks of injury: Loose in the house, crated, x-pen, tethered, muzzled. I'm not sure the safety angle between, say, tethering and muzzling is really all that different. You just have to pick what seems to work and what risks you're comfortable with.

I've gotta say, if he seems to be taking to the tethering so well, I'd stick with that. The beagle rescue I worked with has been advocating for in-home tethering for YEARS. The director himself does it with dogs who cannot be trusted loose, and so far I've never heard of an issue. Obviously there are risks to EVERYTHING, but it sounds like Quid is pretty comfortable with that situation.