It's funny because Trump really tweeted these things.
Donald Trump probably thinks Josh Groban is a loser for going for Jimmy Kimmel Live and singing his most hilarious tweets as piano ballads. From political insights like "@BarackObama's birth certificate is a fraud" to pop culture observations like "Robert Pattinson should not take back Kristen Stewart. She cheated on him like a dog," Trump's writing is poetic and full of surprises—and makes excellent lyrics!
Jimmy Kimmel has correctly identified that there's nothing funnier than the actual things people tweet—when read/sung by someone else. I have to admit this video actually made me LOL IRL.