Is he taking another vacation?
Regardless, imagine if a Democrat did this. They'd be called "Communist sympathizers." Fetterman ought to tar Oz the same way.
Also, might I add how thematically out-of-touch he is still being by apparently assuming that the average person reading his tweet can just drop everything they're doing on a whim, like him, and just travel halfway across the world.
Even if you have a lot of the same dynamics with diasporic politics, the tenor around US-Vietnam relations is very different from, say, Iran or Cuba, and there's been a bipartisan consensus that stronger relations with Vietnam are necessary since rapprochement 20 years ago. Not that I think voters particularly care, but attacking on this front pretty easily opens you up to counters on "being soft on China" and whatnot.