Musk never said you can't put trains in his tunnels. He happens to have a car company to help, but I bet if he had a train company sitting around they would develop something for the tunnels.
Boring company tunnels are wider than London subway tunnels.
Squandering an entire companies potential as a PR move for your other company is hardly big brain executive work though. Film executives do that all the time, and they're some of the dumbest people doing supposedly intellectual work.
Boring company tunnels are wider than London subway tunnels.