Any civilization generally spreads out from a center, with evidence of its presence stronger the closer to that center.
This means that one would expect strong evidence of Mayan presence in the Caribbean, Florida and south Georgia, which AFAIK does not exist, not an isolated presence in north Georgia.
It’s not like they had the option of establishing free-standing colonies supported by air, like ours in Afghanistan and Central Asia.
I’ve read similar accounts of Viking presence in Minnesota or Alberta, with no particular explanation of why they would have bypassed other lands between. When the later Euro settlers of history showed up, it took them centuries to reach these areas.
I would think they didn’t necessarily bypass the lands in between. We’re just stuck with the few places where some evidence has been found. In this case, it seems completely reasonable that Mayans might have travelled all over the Caribbean area and pushed up the coast. I suspect that wide travel and trade was wider and earlier than has often been assumed.