You're right but I'm sure both companies had good reasons for their schedules (for instance noise restrictions at night).
And realistically, from your plane at JFK to Manhattan, that's got to be a least an hour and a half (immigration and cab/limo). And assuming you'd have to be at JFK just an hour before your flight (and for an international flight that's ballsy), plus with transportation still taking an hour, you just wasted 3.5 hours commuting forth and back to the airport.
That schedule wouldn't work unless you flew to Manhattan. And even then, it'd be tight.
Just use Blade helicopter service - 10 min to Manhattan starting at $200+ so affordable to whoever can afford business class. Still tight for one day meeting but if LHR flight was at 8:00AM and flying back a bit later at 2PM NY time it's possible.
I expect operators would arrange dedicated/express facilities for all the airport stuff to speed up the experience. Dedicated/priority check-in, security, immigration. What would be the icing on the cake is an express train from the airport to the city centre that runs every 10-20 minutes (for all passengers prepared to pay, not just supersonics).
That would be the Long Island Rail Road (at 35 minutes). (It's also connected by subway, which will take 60 minutes to Manhattan but maybe worthwhile if you want to get off sooner.)
