Ubiquitin, what do you mean “there was no tzibur”? The tzibbur exists, whether there is a minyan in shul or not. A tzibur is a corporate entity, not an ad hoc minyan. It has a continuing existence, and it has obligations. One of those is that the torah be read in public. Right now most of our tziburim are unable to fulfill that obligation, but one day soon they will be able to, and when that happens they will each have to decide what to do about the missed parshios.
By the way a tzibur is not a shul, either; it’s a kehila. Some kehilos have more than one shul (or more than one minyan in the same shul) but they are all the same tzibur. If one of the shuls belonging that that kehila read the torah and another one didn’t, the common psak is that the shul that missed it does not have to make it up, because the kehila as a whole fulfilled its obligation.