If you think that all that's going on down on the border states is "playing catch and release with Mexican immigrants", then you need to come down here actually see what's going on that isn't getting reported in your daily news. There are some persons and threats coming through that are caught, and many that aren't, that would make your head spin. There are situations, engagements, and other scenarios both with military and military-style forces, as well as cartels and other organized factions, where our outmanned and outgunned CBP can't (and in some cases, aren't allowed to) stop them. Come down and see sometime, it would open your eyes a bit.
So yes, playing masters of the universe around the world with every problem and situation large and small, shouldn't cause there to be a complete ignoring of the realities of what it slipping through central America and across our own "secured" borders. Without going into SIPR, it's a heck of alot more than just a couple of Mexican immigrants looking for work, that you and many others are under the incorrect and assuming impression of.
While I agree with you on not blurring the lines between military and law enforcement to the max extent possible, the military isn't being used for domestic law enforcement; and acting against or being used to counter external threats to this country, shouldn't blur those lines either.
Take care of things overseas as-needed. Don't leave the gate to the yard open while doing it.