The form of your argument is: Tesla says 19th century scientists have flawed thinking about alternating current, Tesla is a 19th century scientist, therefore Tesla has flawed thinking about alternating current.
More generally, no member of any group can ever say that the group is wrong, because they're a member of the group.
But stated differently, the flaw becomes apparent: "No member of any group can ever say that the group consensus is wrong, because they are a member of the group." But the one criticizing isn't a member of the group who shares the consensus, and the contradiction evaporates.
