I'll give you this much: revising the history that we've known all our lives is something that it is both easy and natural to resist. I know it certainly comes into play in my own impulses when conspiracy theories of whatever stripe start being bandied about.
But what would it really mean if a Chinese vessel had touched the shores of the Western hemisphere prior to Christopher Columbus? Not much more than it means that the Vikings did, or if any of
these other pre-Columbian theories might actually be true. The real point is, none of them took. Sure, it would tell us something about the technology and tenacity (or dumb luck?) of those who might have made it earlier than ol' Christoffa, and there could be some ramifications should any of cross-cultural exchange occurred. But it wouldn't change the fact that the events of 1492 - misinterpreted though they were by the man who actually brought them to fruition - are the ones that led to the Americas, and the Europe, and the world that we know today.
And here's the other big thing: there's nothing to change the fact that, from many reports, he wasn't that great a guy, one who retained the power he achieved in the islands with an iron fist, and often incompetently at that. He was greedy, and possibly responsible for the commencement of what many have considered a genocide, and he also <I>never</I> knew what he had actually found.
But that doesn't matter, unless people are still in the business of idolizing him, or holding him up as a hero. He was pivotal, yes, but so was Vespucci, who actually figured out what it was, and everyone who followed, who we all learned about in grade school. (Well, those of us in the continents, anyhow. I can't speak for education elsewhere, and I'd presume it's lacking on this subject, just as non-American colonial history is given much less emphasis, and understandably so, in my experience.) He's part of the <I>story</I>, and that can't be taken away from him. But let's have some sense of who he actually was, and what he actually did, and recognize that the import of the event doesn't offer much in the way of moral reflection on the man.
(All of this, of course, is also leaving aside that he was a Genovesi in employ of Spanish monarchs who never set foot on anything that's part of the United States, a society that he, like so many of his contemporaries, would scarcely have understood nor endorsed.)