I watched this show yesterday on i think A&E. There was an all day marathon of it on. It seems to me that he does know a lot, however most of his knowledge seems to be based on personal encounters in Louisiana. Ball pythons are not native to Louisiana, so it's possible that he knew it was a python because of marking and the shape of the head, however it's also possible that he mistook it for a baby Burmese python. Since Burmese are native to Florida, it's possible to see some in Louisiana.

I also believe that he exaggerates the danger sometimes for added dramatic effect.

It could also be possible that he makes things sound more dangerous than they are simply because he doesn't want people trying to wrangle snakes out of their own houses if they are inexperienced just to get seriously hurt and say "well I saw Billy the Exterminator do it, he says that this kind of snake wasn't harmful."