What brought Justin Sun there in the first place to become Prime Minister?
I don't know. But with this, he can claim that he's a prime minster of a country to boast his popularity and standing. And i would speculate he would try to make Tron as legal payment method.
No doubt he will do everything just to make his token, TRX stay afloat and that includes using his own coin as a legal payment method, and a legal tender on this "country" Liberland.
Speaking of country, I did a quick google search and this Liberland is not officially recognized as a country by any member of the United Nations or by the international community. I also saw that the "country" right now doesn't have any permanent residency, but there are around 400,000 registrations for citizen applications. Whatever the case is, this is only for the sake of Justin Sun, and not for whatever it is.
The good thing about his token though is that it stayed at the top, and we saw an increase in its price despite of it not being talked online... or is it?