Finding a good browser name these days is difficult because you easily get legal issues if it sounds similar to existing ones.
No. This move by Brave to threaten legal action against Braver/Bold is completely ridiculous, and goes against the very nature of free and open source software. Did Firefox threaten Waterfox? Did Chrome threaten Ungoogled Chromium? Did uBlock threaten uBlock Origin? Did KeePass threaten KeePassX or KeePassXC? Did Bitcoin threaten Bitcoin Cash?
The whole point of free and open source software is that anyone can fork it and change/improve your code, especially if your project has started to sell out on its core principles and sell out its users in return for making profit, just as Brave has done. This recent legal action is the most recent in a long line of very questionable decisions from the Brave team.