There are idiots everywhere.
It's too bad it's not as simple as finding a video of the act, then deportation.
No, I think the grammar is correct. They are encouraging the tourist to sleep with Australians not other tourists. 
Quick DNA test on the cigarette butt might be a good start. 🚬🚤 at least they took there rubbish with them and didn't leave the coal embers on the grass.
