First off, I am NOT an attorney, but as I understand it, corporations are created and governed by the laws of the state of incorporation, in your case South Carolina. So a corporation with a name identical to yours could be created in North Carolina. That is why Trademark & Service mark regulations were created, and even then, you must prove you are actually using or marketing the Name in the specific geographic making it confusing for the potential customer to realize the differences between the two companies. In your case as cited by your example ABC, Inc is clearly not the same as ABC.COM, Inc. That is a distinct name although similar to yours, not identical.
Checking with your attorney and applying a little legal muscle may help eliminate their usage, but in today’s complicated system, I’m not sure I’d bet on it.
As you said, maybe it’s just a “rumor.” How many rumors turn out to be true?
America's Favorite Newslesspaper