[not2b]

If someone on a different instance decided to follow a famous celebrity, and Meta tried to attach that celebrity's name to an ad without their permission, the celebrity would sue and it would be a slam-dunk win. Meta can't use someone's name without their permission. Even someone non-famous could sue and win. Some very big companies have gotten into trouble that way. Adding "sponsored content" is not a get-out-of-lawsuit-free card here.

There'd be nothing stopping that celebrity from shilling for a product on their Threads feed and their followers would all get any such shilling. There's already some of that on Mastodon, which is OK if instances permit it (authors, artists and small businesses promoting themselves).