Costello's turn of phrase often involves him repeating clauses of his speech or re-paraphasing them eg.
"If those are not your values, if you want a country which has Sharia law or a theocratic state,"
The phrase
"you should seriously consider a move to another part of this planet."
is very strange speak and Costello would not have said it. He'd have said "another country".
The more I read it, the less it sounds like Costello. And why are there words in capitals? Did Costello say this on his blog? Or did the transcribers just add some poetic licence?
"It is certainly appropriate to display it on the walls of our schools."
No one in Australia's Government has proposed any such measure, that seems to be a uniquely American concern, which suggest to me this was written by some American member of the KKK with a blog.