Syphilis is caused by the Bacteria T palladium, however, the consensus still is that it was an illness brought over from the new world. During the early stages of syphilis being recognized across Europe it was often mistaken for leprosy. A quick google image search will allow you to compare classical-era Roman leper skeletons with ones afflicted with the skeletal effects of syphilis. Some are very different but a number look very similar.

Its not unreasonable to conclude this is a case of leprosy's skeletal effects being "mistaken" for syphilis. Two factors seem probably causes, the lavish brothel in Pompeii naturally directs the mind to a topic. So one excavating the skeletons of lepers who had bone damage similar to syphilis, they perhaps made the connection subconsciously due to sex already being on the brain? It may be that, or it may be the fact that if you say you've found hard evidence of pre-Colombian syphilis you get a lot of publicity for your otherwise fairly pedestrian documentary. None of this conjecture has passed peer review as yet though, so it's perfectly possible like the many previous examples of "pre-Colombian syphilis" victims, it's not going to stand up to rational academic scrutiny. But until then, ultimately, the jury is out.

Also, just because a disease looks like syphilis does not mean it is caused by T. Palladium and could simply be a now extinct disease which had evolved similar symptoms; this wouldn't undermine any New World origin theories. The problem is we have no samples of the bacteria available from the skeletons which would be conclusive proof so rely on interpretation of skeletal damage, which really makes it just educated guesswork since other diseases produce very similar damage as noted.

If it were true that the Romans had syphilis it would naturally undermine he prevailing new-world theory. But if the Romans had a syphilis-like disease, but not from the same bacteria things would remain unrocked in the boat.

As an addendum to this question, would that not also invalidate the theory that syphilis was a New World disease?