I work for an exotics vet that sees a lot of snakes, and since I've been there, he's never prescribed it. I don't think we even carry it. So I can't say one way or another on its safety or effectiveness. However, what we often do at our clinic is prescribe a round of antibiotics and if it doesn't improve in a week or two, to absolutely get a culture done and change meds if needed. A lot of the people we see have money constraints and even though we explain to them that it'll probably be safer and cheaper to do the culture right off the bat rather than waste money on meds that might not work, they often just want to try the meds most likely to work, namely Baytril or Fortaz.
If you trust this vet to give you correct advice and the proper dosage to use, even without seeing the snake, that's your prerogative.
From what I've read about issues with Baytril the problem is that if it's not injected properly into the muscle it can cause subcutaneous tissue damage. We show our clients the proper way to give it by giving the first dose, and telling them about the dangers of not doing it right, and that if they are AT ALL nervous to come in and we'll give the injection at no charge.