You say that as if Garland wasn't the one who appointed Smith.
It's not as if Smith acted on his own. Yes, things were being done behind the scenes before Smith, including the behind the scenes work to make that appointment itself.
There are questions about why Garland moved so slowly, and arguments that it was strategic timing that didn't work out.
As for Cannon, we can be pretty certain that they DID move in that direction internally, but the removal of a judge in a situation like this is nearly impossible, so they were still building the case.