Contacts at and policy at AGBell (and support services at events) have only supported and encouraged my family's use of ASL and our choice in educating Li-Li bilingually. I don't have a long history, but in 3 years, I've NEVER once encountered anyone representing AGB who is anti-ASL, overtly or otherwise. They do advise that we speak to someone at Gallaudet, a local school for the deaf, or NAD for specific ASL-related questions as they don't claim to be experts or the go-to resource for ASL, which seems very responsible to me.
I've also never had a medical professional advise against sign and every audiologist and SLP we've had has been fluent in sign.
I have had a parent of a now-adult CI user question why I spent valuable time pursuing an ASL-based educational environment when we could have been interacting with spoken language at home or could have my daughter at a school much closer to our home, but that person had no official affiliation with AGBell.