Mate, I don't think that he's the owner of any corporations yet. Anyway, I must admit that he surely can get mortgage loan even if he's a trader. Why not? If he has a good deposit he can get mortgage with kind of 40-45%. However, he doesn't need to forget that they will need to submit a full tax...
That's the price Australia paid involving in a trade war along with US. Now US tries to make aussies switching to green energy under the threat of sanctions.