You are right. The number of nodes in our cluster is equal to the replication factor. For that reason I think it should be sufficient to call sstableloader only from one node.
The next question is then: do you care about consistency of data restored from one snapshot? Is the snapshot taken after repair? Do you still write to those tables?
In other words, your data will be consistent after restoring from one node's snapshot only if you were writing with consistency level ALL (or equal to your replication factor and, transitively, to the number of nodes).