I don't know if there's a name for it, but while not naked, it's still a dubious situation unless Bob has secured some way to get the share back to Alice when Alice wants it back. Say Charlie has decided to go hold that share forever; how is Alice ever made whole?
In the only-one-share-exists situation, there's no real way out of that. In a situation where more than one share exists, Bob could, say, obtain a call option so that he at least has a plausible way to acquire a share in the future to make Alice whole.
This results in a similar situation to GME where the short interest is > 100%. WSB wants to be Charlie. They want to hold the share that Bob is legally obligated to buy and can't purchase anywhere else. They can then demand whatever price they want for it.
In the only-one-share-exists situation, there's no real way out of that. In a situation where more than one share exists, Bob could, say, obtain a call option so that he at least has a plausible way to acquire a share in the future to make Alice whole.