The Supreme Court is as political as the rest of the country. I believe the reason the SC punted is because they, like everyone else, appear to be saying that the Trump agenda is illegitimate. They punted because the election are coming in November and if the Dems win the House and/or the Senate the agenda is dead. The SC is delaying Trump just like the Republican House and Senate.
To your point, you are right, DACA is not law. The SC is in effect legislating from the bench again (like the ACA). The precedent they are setting is to make the DACA EO law. Horrible