You could speculate that he is trying to make a name for himself, so that the upcoming games would make him a stable income. As an indie developer he should know the fact that Flappy Bird won't last long - for example, Rovio is making over half of its income from other physical brand items. I'm not saying you will see Flappy Bird soda next year, but the games Dong releases later will most likely gain more attention thanks to Flappy Bird and Twitter is a way to make sure that the fans will notice it.
$50k a day ... even if it only runs a couple weeks ... is beyond "stable" for Vietnam. As a reference-point, the average monthly income in that country is under $200.
Are you speculating that, or are you suggesting that others should speculate that?
WoodenChair, your request for calm is greatly appreciated.