The Hollywood actor is a prominent donor to the Democratic Party in the United States. In recent years, that has regularly led to criticism from President Trump, who has called him a “second-rate movie star,” among other things. According to Clooney, it didn’t bother him much. “It’s not my job to keep the President of the United States happy.”
Cool to see he already knew back then (this is a comple guess, of course) that getting out of the US was needed. If this was the plan all along it still took this long, but there are obviously many more things than just the citizenship to make a move like that.