I think you meant to say, "This issue has truly exposed our boss for the ability he has". 'expose' means to make something visible that was hidden before. In your example, your bosses ability was hidden - before this issue, it wasn't clear whether he had it or didn't have it. It was not possible to see or tell if he had it or not. Then this issue arrived and it uncovered (or showed) his ability or lack of ability.

Thank you.

Your example sentence does not really make sense. “To expose N1 for the N2 it is” means that the true nature of N1 was revealed to be N2. For example, you could say, “This issue has truly exposed our boss for the liar he is.” This would mean that the boss is and always has been a liar, but it was made clear because of the “issue”.