There is a lot to unpack here, and whenever there is a Cadet Corps, things get confusing.
When the NROTC scholarship application went through, is it true that the major listed on the application is the same one that he currently has? Is that Tier 1 or 2 or 3?
What was the specific reason given that NROTC would not accept the current major? Is it because of a Tier shift, or because it would require an extra semester, or something else?
The NROTC scholarship covers tuition and fees, so I am not sure where the leadership scholarship is coming from. Does that pay room and board? Are there additional requirements for the leadership scholarship?
If the LT Ambassador states NROTC would cover an extra semester, I am struggling to figure out why any university would say no or state they don't do that. It's just extra money for them.
So for me this is just a confusing post that needs more background for a better answer. Best thing is to have him ask to meet with the unit XO or PNS to get a better explanation. But this just doesn't sound like it's the whole story somehow.