Whether that argument would hold up in court remains to be seen, of course.
Most of what I see being complained about can easily fall under socioeconomic development, which is ostensibly one of the objectives.
The executive branch doesn't get to interpret what spending is in line with the laws passed by Congress.
Trump is taking a shit on the US Constitution.
> Although one commentator characterizes the case's implications as meaning "[t]he president cannot frustrate the will of Congress by killing a program through impoundment,"[2] the Court majority itself made no categorical constitutional pronouncement about impoundment power but focused on the statute's language and legislative history.
But they don't strictly speaking have to overturn it, just limit its scope of application somehow. For example, Train was about grants to the states – SCOTUS might rule the Congressional Budget and Impoundment Control Act of 1974 unconstitutional, and decide that the President has the right in general to impound appropriated funds, but they also might follow Train in carving out an exception to that general right for grants to the states.