They are going through proper channels. What he is doing is signing an Executive Order allowing him to close those channels when the border is overwhelmed. This is a complicated situation and I don't think this is generally a good move. I would rather see more resources put towards processing immigrants so that the border doesn't get overwhelmed in the first place.
Honestly, I think that this is a purely political maneuver to make the Republicans look like fools, not that they need help with that. They have constantly been screeching about the border crisis and invasions, and such nonsense, then they bowed to their orange lord and tanked the bipartisan immigration bill in the house. I suspect that Biden is taking this step so that every time they squeal about the border, he can point out that while they do nothing but block solutions, he is actually doing something. Just signing the order is enough. He never even has to implement it.