If the lawyers don't recommend you add the banner, and you somehow run into trouble because of it, the lawyers will be blamed. However, if they do recommend that you add a banner and you follow their advice, then they can get some more billable hours by recommending some verbiage for the banner, checking your website to make sure the banner is displayed in a compliant way, etc. And even if you don't follow their advice - people rarely fire their lawyer for recommending caution.

So, how did you ever expect the lawyers not to recommend adding the banner? That's like going to a plumber and ask them if you should DIY or not some installation. Of course they're going to recommend you get a professional...