I'm not sure you read the proposal in the original link, as these questions are addressed there. I'll answer them here as well.
I read it, I just didn't find much value in any of it.
The AAC already has Navy as a football only member. The Big East TV money would more than offset losing the AAC deal for UConn. UConn may be better off with the Big East option, so for Aresco, is the membership better off with the proposal, or losing UConn altogether? If UConn leaves, who does the AAC pick up to replace UConn, and have that add be greater than UConn's value? I argue that the AAC is better off accommodating UConn. What if others wanted to leave and be football only? UConn is in a unique situation. Where is Cincy going to go? The P5 is the only better option for most.
First Navy is unique because they were invited as a partial member. They weren't a full member who would suddenly decide to look elsewhere for a better fit for some of its teams like Uconn would be. A huge portion of Uconn's Value to The AAC is tied up in their elite M/W Basketball Teams being a part of the conference. The AAC is supposed to just be OK with being a placeholder for Husky Football while they reap no financial benefit from Husky Bball? Unlikely.
As for who could The AAC replace Uconn Football with, how about Umass? Are SMU or Tulsa Fans going to travel to either of these schools? Is Uconn Football going to be that much more of a draw than Umass to the southern or western members? The AAC could potentially target Army Football with Wichita State Basketball. I think that would be an interesting idea to many. The point is that there would be options.
As for the idea that no one else would care what Uconn did, because they themselves have no better options seems nebulous at best. JMO but I call BS on any other member being OK with Uconn getting preferential treatment. If The AAC continues to pay out peanuts, a number of schools might entertain being aligned with more regional conferences. At that point bye bye AAC.
To your second part, if the AAC was to proactively expand, it isn't crazy that two top end FCS programs would be on similar consideration as C-USA or MAC outliers. Adding 2 in the northern footprint reduces the division footprint that is a common complaint in the AAC. Playing more teams in your division footprint and fewer cross division reduces the travel, and reduces the frequency of playing the south division schools which seem to be the complaint of many on the board. Would playing Nova and JMU instead of Tulsa, Tulane, and SMU be better or worse? Again, is the AAC better with this scenario, or losing UConn altogether?
Why would a conference making little revenue want to further dilute that stream by adding two teams that have no chance of bringing anything of value to the table? The AAC would be better off courting Army and Air Force as they at least have a brand that people are familiar with and potentially excited to see on the schedule. Nobody outside of maybe Temple is going to be excited to see Nova or JMU on a schedule. They will immediately become the two games that nobody cares about seeing live. I'm not trying to be harsh, just honest. There is literally no value in either of these teams for The AAC.
Finally, as UConn knows the financials of FCS aren't a no brainer either. FCS has no added revenue potential. Struggling withe a $7M football expense with no hope of revenue and uninteresting opponents is worse than spending $12M, having opportunity for revenue, and playing football that matters. Temple is Nova's natural rival - playing for the Mayor's Cup on equal FBS footing would be good for football in Philly, would be good for both programs, and would be good for the AAC.
JMO but funding 85 Scholarships and the looming expense of full cost of attendance could greatly offset the majority of income that being in FBS might generate. That said how again does Nova and JMU generate more money for current AAC Members? I don't see it. Not from TV or potentially ticket sales. The only concession Nova would make for joining The AAC would be to play one neutral site game against an AAC Opponent. WTF is that supposed to do? Honestly who cares about one meaningless early season basketball game? How is that payment for carrying the weight of a new FBS Football Program?
Whether it be basketball or football, rivalries matter. This point is often lost in CR. Who are BC's rivals now? Who are UConn's rivals now? This proposal is a win for UConn, a win for Nova, a win for the AAC, and a win for the Big East.
I agree that rivalries matter. If they matter enough eventually they will be scheduled. Uconn is playing both Umass and BC on future schedules. If the Mayor's Cup is actually important the schools will schedule it. That game in an of itself is not worth inflicting on the world JMU vs SMU, Nova vs Tulsa or any number of games that would generate zero interest at the box office or on your cable box.