As insensitive and unsatisfactory as the Dad's response was in all this, let's keep a little bit of perspective. I would hesitate to advise any parent to give a 9 year old a hat in hand apology for what was a lapse in good judgment. Something about that idea doesn't sit right with me, and it might do more harm in the long run than good. Remember that he is the kid's father and that position demands a certain respect even when he doesn't behave worthily of it.

I'm sorry this happened. It sounds awful for your DS, you, and your DH. Yes, awful for your DH as it isn't something he wants to be remembered for I'm sure. It's good that he feels bad about it! I hope he does apologize to your DS and tries to make up for it in some way. Let the poor little guy know it won't happen again.
Nine, 29 or 59, having just gotten over this bug you don't ask the one who's sick to clean up a mess like that. 
