Can’t speak for this specific instance of course, but in the UK you occasionally get people flying messages over football ⚽ grounds or whatever, and I have read more than once that the company doing the flying don’t actually know what message they are pulling - they just get the packaged up message and fly it where the customer asks them to.

Don’t know if that’s true, though and it’s arguable whether that absolves them completely of responsibility for the message being shown.

EDIT - that being said, the first example I found contradicts me - here, the message was known by everyone, including the pilot!

https://www.bbc.co.uk/sport/football/26783751

EDIT 2 - a particularly nasty example here, where someone mentions banners not being checked. They definitely should have been.

https://news.sky.com/story/outraged-airport-bans-banner-flights-after-white-lives-matter-burnley-stunt-12013293

“Due to the nature of the activity, banners are not checked before take-off and the content is at the operator’s discretion.”