American's sue at the drop of a hat, just because lawyers are fishing around to see if anyone is interested in a lawsuit doesn't mean there's substance behind it. Often they're just looking for a company to settle so that it doesn't drag on.
When All Birds came to market they were unique and they also were a hit with certain celebrities and wealthy clients, now there's dozens of companies making natural footware to compete with them. They're no longer unique in the marketplace and the buzz has worn off.
I'm sure Brown is still a very welathy man, but the value of his shares in all birds are now something like 5% what they were at their peak.