Knowing the restriction goes to 18k certainly says that either S-A or A-S reach must be limited but the as your post points out no buffer between MANPAD actual range and the limit imposed. I think unlikely to say MANPAD, specifically.

There's a small private airfield to the west with only a single victor airway connecting to el-paso. the victors end at 17999 ft, effectively cutting traffic for non-commercial or non-business jet operators.

Closure of the victor airway there seems, again limiting airborne craft due to airborne hazards.

Hazards in the air, near the surface that are, seemingly, unplanned with a cone pointing at mexico.

That's kind of the most anyone will get until more info, could be some urgent testing of some capability or response to small craft (drones) coming over the boarder. Emergency timing could be to garner interest or emphasize importance, which works well politically.

Las Cruces International Airport and Dana Jetport are unaffected.

The restriction goes to 18k because that's the top of VFR space. Anyone operating above 18k has to be on an IFR clearance and under positive ATC control. That makes it easy for the feds to make a call and say "Hey, center, get everyone out of this airspace" wheras in the VFR altitudes it's very difficult for them to legally clear the space since a VFR plane could be flying around not talking to anyone.

I only know about Las Cruces from the Organ Mountain Outfitters training material in the DaVinci Resolve sample footage. Sadly they closed a few months ago, which is a shame because I never got my arse in gear to order a shirt from them.