I am so sorry thnx, that you have the added strain of this on top of his walking out.
I am sure that in his employment file, it will give the real reason for his instant dismissal, as it would be required for their own legal safety.
You also have the fact that he voluntarily surrendered his unsupervised visitation, and You have the AA log to back up your word that he has drink problems, and that he knows this.... or why would he be attending AA at all.
As for his counselor describing him as being "low risk for relapse", where on earth did he get that idea from? If he is an A, unless he is doing more than going to meetings and is totally committed to sobriety....he is a relapse risk.
You are worried about him whilst having visitation, especially in regard to your daughter and her siezures, and this is a valid concern.
Have you discussed this all with your lawyer yet? Until you have some answers from him about visitation, and AH's AA documents etc, you really can't know what the situation is and you could be worrying without need.
I would see my lawyer, if necessary get him to contact your ah's ex employer and get some documentation re his dismissal and any evidence you can as to his problem drinking, and continue on from there.