It is a darkly amusing irony. Via The Australian:
You might refer to him as “Scott”. Possibly the Prime Minister. Maybe just “the PM”. People on both sides of the political fence often use the abbreviation “ScoMo”. But for a growing number of Australians there is a different way to refer to our current Prime Minister.
He is now “Scotty from Marketing”. Across social media and in day-to-day conversations, more and more people are using the phrase. It’s already proven immensely popular on Twitter, with #ScottyfromMarketing trending several times over the festive period. And there seems little doubt that as 2020 progresses use of the nickname will become even more prevalent.