Granted I think she said that you're not allowed to let them roam free at all so maybe she misunderstood, or maybe the law has been changed since.

Seems like you're required to keep them indoors during the outbreak of a disease like bird flu - there's mention of this in the section right after the part you quoted.

I think the rules about having some form of enclosure are fairly sensible and probably not incompatible with an acceptable life for the birds. I'd guess a fence around your property would suffice, after all, which would simultaneously serve to make sure that none of your birds get lost.