First things first, that lady is full of crap. Don't listen to her.

What city do you live in? They are some places when keeping pythons is illegal, but there are also places where you're just required to have a permit.

A tub is a perfectly fine cage for a BP, breeder or not, as long as it is set up properly. It does need to have air holes placed, preferably melted with a soldering iron rather than drilled, so that there are no sharp edges. A tub is also easier to keep at a proper temperature and humidity. Tanks are "ok", but they need more modification and upkeep to properly house a BP.

If you are getting info from reptile forums (especially this one ), caresheets, and such, you are already 10 steps ahead of most people, and you are probably doing just fine.