I think I have an idea of what you’re referring to here, but aside from the leaked comment that clearly forced his hand to leave BGT, I don’t think I’ve ever seen anything that might be considered ‘deeply troubling’ reported about Walliams beyond social media? Which by the way, I also don’t use. ;-)
Agreed that it’s notable that the area has not been expanded. Whether that's due to Merlin's cycle of investment and perhaps their loose definition of a 'world' or cautious brand protection, I couldn't tell you.