His excuse is flimsy. That's why I think the people of DC voting for it overwhelmingly could change his mind. Puerto Rico would not have the "district" problem. It's just a plain old territory like most states were when they asked for admission. I wonder how the local sentiment is running. Becoming a state could have some huge advantages for the people of Puerto Rico.
If everybody who moved to the mainland moved back temporarily, I'm sure the statehood vote would pass. Most of the people who see an advantage of living in a state simply moved to the mainland.
We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.