Its funny when you think about whats fair in this kind of stuff. For example if you use AppleSomething, apple is a fruit, was a famous record label before being a famous computing brand.

As theres a fruit before anything else, you can argue why you could have some rights over the brand. If is AppleOS of course you can have trouble because Apple the IT company have a OS and they might argue this is a common way people refer to iOS or MacOS.

But Lego is a whole different category. There is no well known concept of Lego before Lego was created, and theres a sort of mechanics and way of thinking that is totally associated with the idea of Lego because of the Lego toy.

So if you use Lego in that sense even if its for something else, they might reclaim the concepts name, because they actually invented not just a toy, but a toy with a concept of composability for which people might be inclined to reuse the name, not because of the toy, but the larger concept the toy represents.