Saying it is a typographical error suggests the typist made the mistake. I expect a secretary typed up the letter as dictated by TCAS and therefore the error is not likely a typographical mistake it is a grammatical error and/or a wording error.
If it is a typographical error then TCAS is suggesting he typed it himself and therefore has shown he isn't even worth a secretary's salary as he should have proof read his work before distributing it to the entire pilot workforce.
Furthermore, a secretary doesn't get 4x bonus - and neither should he!