To be fair, the author is definitely not arguing that America was discovered by Africans 3000 years ago. He is just providing some background regarding the controversy of who discovered and named the Americas. He also writes:

> Further, other discoveries of America have been credited to the Irish who had sailed to a land they called Iargalon, the land beyond the sunset, and to the Phoenicians who purportedly came here before the Norse.

I think his use of "it has been argued", "have been credited to", and "purportedly" in this context are not weaselly, and are fine in reference to unsubstantiated arguments that people have made. The author is clear though that the only two undisputed discoveries of the Americas prior to Columbus were by the Asian forebears of Native Americans and the Norse:

> They were of course preceded by the pre-historic Asian forebears of Native Americans, who migrated across some ice-bridge in the Bering Straits or over the stepping stones of the Aleutian Islands.

> the remains of an 11th-century Norse settlement in Newfoundland, excavated in the 1960s, that forms the only undisputed evidence of the first European presence in the New World.