...snip..
Umm, you should ask a knowledgeable greenie what grows their natively. All you could really be asked is to plant endemic species (what occurs there naturally) from endemic seed/sources. i.e. the genetic make up should be plants from the same valley/next valley and no further. Anything else is just bullshit.
I would also be taking in aerial photographs of his property before he started, as many as you can collect going back as many years as possible. This provides the bench mark.
I have always found when dealing with shiny arses that it helps to take notes of who said what at the meeting. It sure changes the tone. Also helps to respond to their queries by letters to the local newspaper (if you are a public body).