Morrison has nothing to lose by attacking Andrews. Victoria voted for the ALP in the last election, it's not like we're a swing state.
Maybe the LNP wants an outbreak in Labor-voting States? If there's one thing I've noticed about LNP voters in the last few years, it's that if you're not with them, you're demonised as the enemy and your opinion is incorrect on all issues and you are classified as an unacceptable risk to our fragile society. There's no room for a range of opinions in an LNP world. The conservative right is far more extreme and intolerant in this country than it was 20 years ago.