Adding to what Blondie has said, Watchtower officially takes no stand against such groups as AA.
In order to prove that a particular person was involved in interfaith or false worship, someone would have to attend the AA meeting he/she also attends. And they would be violating the anonymous part by reporting to any group of JW elders what took place with another AA member. Too many problems for them. I am sure Watchtower lawyers would say to "drop it."
Keep in mind that no matter what reasons they give, such as not wanting to interfere in treatments, the real reason Watchtower would take no stand is so that they are not sued over preventing such a needed personal treatment and someone committing suicide or a crime afterward or being disfellowshipped for their drunkiness alledgedly because Watchtower banned their needed help.