Apology via Email / Not Allowed to Respond?

Not necessarily insincere... maybe the person just wanted to make sure you'd pay attention to the apology and was afraid if they gave it in person you'd dissuade them or be uncomfortable. As for not wanting you to respond there could be a number of reasons, not really knowing the full situation it's hard to say. It does seem unusual though. Maybe they just enjoy being verrrrry dramatic!