No doubt, the site at Flushing Meadows was already in place since 1938, and it cost virtually nothing to prepare the land for a ballpark 25 years later. And I must admit, by the early 1960s, Moses was falling from grace, to which his unfinished projects can attest (Sheridan Expressway, Prospect Expressway, Clearview Expressway, Seaford-Oyster Bay Expressway, etc.).
On the other hand, the exchanges between O'Malley and Moses began well before the Dodgers finally won in '55, when Moses was still in full control of what and what didn't get built. Did Robert care about the cost in the Bronx when he literally cut a straight deep swath through bedrock upon which neighborhoods had been generational? Did he care about the folks who once lived on Horace Harding Blvd? Looking at a map, and considering all Moses had built already, it doesn't seem like a reach to think he could've built a highway from JFK along S. Conduit and straight across the already-widened Atlantic Avenue. To this day, I wish a highway like that existed.
I believe that, by the mid-1950s, Moses had already cost the city taxpayers plenty, and, imo, the highways I would propose would've been viewed by the city at the time as yet another Robert Moses highway-building project in south Queens and Brooklyn. Needless to say, to this day, it's a pain in the neck to get from JFK to downtown Brooklyn by car. As Ed intimated above, if Moses had felt it was important enough, those highways would've been built and O'Malley would have most likely built his dream park in Brooklyn instead of LA. Had Moses not been adamant about "Flushing or Nothing," we may be following the Los Angeles Senators and the Minnesota Giants. I'm not saying O'Malley was an innocent bystander, and sure, he could've brought the "New York Dodgers" to Queens, but the fact remains that he (and every other land owner in New York) had to get on his knees in front of holier-than-thou Moses to plead his case. Being dismissed time and again, I find it understandable why O'Malley had had enough. Even Mayor Wagner, as you know, had no power to tell Moses what he could and couldn't build. Moses had the final word for over four decades. Unfortunately, Moses wasn't greedy for money. His greed was for power.
As for the exits and entrances, they would have most likely been the usual short exit and even shorter acceleration ramps he'd been designing in the city for years (unlike Long Island, Westchester, SW Connecticut, and Niagara Falls, which had, for the most part, enough land to build those dreaded clover-leaves we all despise [and are still too short]). Anyone who's ever driven to the Brooklyn courthouses knows that for Moses, egressions and ingressions were trivial matters. One look at the FDR Expressway, the Cross Bronx Expressway, or that monstrosity of an interchange with the Van Wyck, Grand Central, Jackie Rob, Queens Blvd, Main Street, and Union Turnpike, and it becomes evident that getting on and off were the least of Moses' design issues. Either that, or he was on some serious medications, heh.
However, to return to your original point in the above post, you're right, the Northern Blvd bypass was much easier to build than the highways I would've advocated. As well, as I hinted earlier, it's much easier to get to Flushing from both NYC airports than it would've been (and still is) to get to downtown Brooklyn. So, in that regard, I'll agree that Flushing was a good choice, especially since air travel quickly became the transport of choice (rather than the trains and buses). Ironically enough, that same jet age made it possible for teams to routinely travel to and from the west coast.
Btw, I didn't know that fact about the meeting that would've taken place were it not for WWII. That, imho, is a truly fascinating fact!
"And their chances of getting back into this ballgame are growing dimmer by the batter."
Put it in the books.