The question is about doing something illegal, such as removing a covenant that was involved in a sale when reselling? If it is something that could have been objected to by the original seller (they would have had standing to sue) and they have not agreed to change the covenant (because they are dead), it seems as if anyone affected should be able to sue.
The breaking of the covenant is what is being sued over.
> Presuming the land is zoned for a datacenter, the datacenter is allowed to do datacenter things.
If my house is zoned for a possible datacenter, that doesn't mean that anyone can build a datacenter there - it is still my house. If there is a covenant that says that the land will be a park, that's the "zoning" by the seller being stricter than local zoning, which means that it also conforms to local zoning.
The zoning doesn't say "The land must be a datacenter."
edit: It would be bizarre if we can sue over terms of service as if they constitute law, but we couldn't sue over terms of sale. I can sue Facebook if they allow another user to violate their terms of service.