2. It's a big deal to you, and a very vocal minority. It's a big deal TO YOU. And guess what? Most people care way more about a 5e DND game "Set in the BG world" (Which isn't actually a thing. Baldur's Gate is a city. In Faerun. It's been revisited in all sorts of other media, and those 2 games don't have a monopoly on it).
Are you able to quantify the "very vocal minority"?
Are you able to quantify the "Most people" who care more about a 5e D&D game?
I agree with you that Baldur´s Gate is a city at the Sword Coast in Faerûn in the Forgotten Realms. I also agree that it´s been revisited in other medias. It´s also right, that BG1 and BG2 don´t have a monopoly on it´s name. But the question is - at least for me - why is it called Baldur´s Gate III?
I don't think he can. In every social media and forums there are huge uproar and it's not vocal minority at all. People have legitimate concerns. He's just trying to intimidate or silence people so that it may appear as small problems.