In your original scenario, why couldn't you have removed the elbow as opposed to removing the nipple?
I've got a couple of rentals with old plumbing like that. No shut off valves and old pipes. What I've done in the past is to bring a sawzall, cut the galvanized back from the faucet, unscrew the cut pipe put in a nipple and install a shut off for the faucet so I can turn on the water to the rest of the building when I mess with the faucet replacement. May not have been possible in this case but I'm always thinking of ways to save my ass if I start digging into that old plumbing and I have to shut off the water to the whole building.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13