The post referencing swimming highlights the problems with using nationals as the definitive test.
Example-
2004 OG trials, Ian Thorpe, reigning world record holder in 400m freestyle false-starts in heats and is disqualified from event, therefore is not eligible for selection.
The swimmer who went on to win & was selected happened to also qualify for the Games in another event, and declined to accept his 400m spot.
Swimming Australia used discretion to name Thorpe (who had already qualified in other events) as our 400m representative.
He went on to win gold.
Now, had Thorpe not qualified to the team in other events (making him eligible to be added to the 400m given the availability of a spot) and had Stevens (the other athlete, who was not capable of being in Olympic medal contention in the 400m) not chosen to step aside, Aus would have stuck by their rules and lost a virtually guaranteed OGM.
Point being, the counting of only one event to test readiness, while guaranteeing transparency, can backfire in the event of disaster (the lost skates example, sudden outbreak of gastric illness, etc).
Is there room though to argue that someone worthy of a gold medal should not be making mistakes (such as a false start) at trials? Of course.
I would say that if nationals are to be used as the sole qualifier, they should be
A) close enough to the Games for the skaters to be in the actual shape/readiness they will be in for the Games, which allows for both an accurate assessment of their ability, and sees them only have to undergo one taper
B) followed by a seperate verification competition if necessary for athletes who were injured/ill etc at nationals, kind of like how USA Gymnastics verify their athletes, however this discretion should only be used in extreme circumstances and should have very transparent criteria.