I doubt if anything "medical" was going on, pilot's comms were pretty good for a non-native speaker.
If you look at the previous 30 or so flights:
* none were in the dark, except on its home-base (Monterrey)
* no go-arounds
* look all more like instrument (or radar vectored) approaches
KVGT has only medium runway edgelights and 3° PAPI, no approach lights.
The airport in the middle of a 'sea of lights'
The 2 main roads immediately adjacent to the airport, are oriented and intersecting almost identical to the 2 main runways.
They came in initially at speeds around 190 (GS, but wind pretty calm), and only after a few attempts, it stabilized more or less below 150.
If it is the same crew that flew all the other flights, I would not be surprised that their recent visual night-flying experience/skills were low, came in (mentally) unprepared and fast, had difficulty establishing and maintaining visual contact with the airfield, and some degree of spatial disorientation.
If ATC was able/allowed to give vectors for a visual approach, they should have done that after the first attempt or two.
And switching off the 30R runway's lights, might have been a good idea (especially as they were overshooting the final of 30L a couple of times)
Everybody is applauding ATC, but I don't know, they were sitting in their familiar TWR, low traffic and but the disoriented pilots maybe the first time in Vegas and at night, in a fast Citation....
Some examples where I think ATC might have improved to score a "very good"
"Turn right to lineup with downwind" (better and more precise: turn right heading 120° to....)
"Continue that present heading 070" (3 seconds later: Correction 250)
"Begin a left turn now 45° to line up" (if a pilot is confused/getting lost, don't mix course adjustment degrees, with heading degrees - although the pilot seemed to understand/acknowledge everything correctly, so not an issue in this case)
"Continue northbound, just continue your heading northbound" (but only a few moments later ) "I told you to fly the heading, you're going northbound now" (!!!??? pretty confusing, even from the armchair)
(while still north of the field -tail towards the field, so no visual- and northbound, in sort of a very wide right crosswind for 30L) "Begin a left turn to enter a left base - correction a left crosswind for runway 30L"
"Turn right 25° for the crosswind, you're about to line up for runway 12L." (again mixing adjustment degrees and heading between instructions) "Traffic is a helicopter over the field" (all the pilots needed, some other traffic to watch out for)
(on one of the failed attempts, overshooting the final) "continue left turn over the field to join left downwind" (but that makes them lose visual after crossing the field, better would have been to let them continue circle -lefthand- the field so that the left seater could maintain visual on the rwy all the time, and better estimate&fly the downwind entry)