Schumer opposes changing the law so as to keep families together because he says Trump could just choose to keep families together. I have no idea how Cruz’s bill would work but that’s a bad argument.
It will probably legitimize a mostly terrible immigration plan in the process, and he’s right that Trump could end this in a heartbeat. If legislation is what it takes because of our dictator’s unwillingness to act, then I agree that congress should do it.