This is dependent on a short range and unreliable local network.
This would not be a show-stopper if enough people made use of it, where statistically some of them always change locations and thus data could be stored-and-forwarded at times.
But I see a different show-stopper: The tragedy of the commons. If such network attracted a lot of users, it would also attract the scum of the Internet - advertisers, for example, who would immediately try to abuse this network for molesting people with endless SPAM messages. It would really take some very clever mechanisms to build a "web of trust" that on one hand would not prevent people to communicate with each other for the first time, while on the other hand preventing that advertiser scum from abusing the network.
BTW, "Swift" is a strange choice if Jack wanted developers outside of the Apple walled garden to take notice. The average Apple user is about the last person to switch from being parented by Apple to some anarchic new network protocol.
The moon is a planet just like the Earth, only it is even deader.