Advertising isn't covered by the ADA. That's the beginning and end of it. Yes, they should. No, they don't have to. Just like liquor stores don't have to hide their advertising. You've also assumed way too much about how broad the website accessibility statues are. They are very narrow, and the case you've presented is not covered by them. Websites aren't required to censor their content for fear it may trigger a response in a disabled person. They are only required to ensure that the website is accessible to the disabled person. If what you proposed were the case, then no alcohol manufacturer or store would be able to have a website.