If Rohrabacher-Farr doesn't expire, the states will challenge the action as a violation of federal statute (where they've won before against the Feds trying to narrowly interpret Rohrabacher-Farr) rather than launching a Constitutional challenge of on grounds where there is crystal clear Supreme Court precedent against them, and little reason to believe the Court has moved in their favor.

Even if they also raise the Constitutional argument, a Court that fears public opinion as much as you suggest would likely take the less precedent-disturbing approach to the popular result by resting a decision on Rohrabacher-Farr (even if that took a somewhat expansive interpretation of that prohibition on DoJ use of funds) rather than overturning Gonzalez v. Raich.