JMO
I think you are right that he may have been trying to do something that would help him get selected and to stand out from other applicants. It fits into this description on this article below.
I hope the idea to try to climb that mountain with minimal gear is not a common idea that is passed around the cadet candidates. Maybe that idea has been successfully used before by the candidates to get accepted and it may be suggested amongst the candidates as something to try and do. That would be awful if he felt he needed to do that to stand out and get accepted.
"Many casual hikers attempt Longs despite the fact it is one of the toughest 14ers. Longs Peak casts a siren’s song over many people who are looking to test their mettle in the mountains."
"More than 60 people have died on Longs Peak and the majority of those have been on the Keyhole route."
10 Things to Know Before Hiking Longs Peak
ETA - I am now curious if we could ever find out of the 60 people that have died how many of them were cadet candidates.