Well - if that (bit in bold) all happened very quickly, I imagine people wanting to maintain a human-survivable ecosystem would be prepared for scrapping remaining flying to be lower down the list of priorities. The problem is that most "live like there's no tomorrow" people [and if we carry on as now there won't be, of course] scream in horror at even those steps to rein in flying.
By the way, why would anyone not have "a vested interest in transitioning away from fossil fuels"? Vested interest doesn't only mean a financial one. My vested interest in that (and in consuming minimal amounts of animal-derived food, never buying things new if old ones can be repaired, not using a car, not breeding, etc etc etc) is on the basis that it would be good if our species was able to live on this planet in reasonable security and comfort for a few more generations yet.
I think we all know where the real financial vested interests are in this debate...
PS - I'm fascinated by the claim that "the loudest on carbon emissions generally support open borders". Where is that statistic from?
I mean an immediate financial interest because if someones income is dependent on energy transition they are naturally going to be strong advocates for any measure that supports their job.
The Green parties immigration policy is essentially open borders. They object to visas being used to limit economic migration and to visas assessing people based on skills and experience. Their refugee policy is essentially that the UK takes as many people as we can cope with. They don't appear to have a policy that refugees should move back home if their country becomes safe. When their home country becomes safe that means flying home for visits. I can understand the appeal of these policies but seems to have been no analysis of the effect this will have on aviation emissions. This is an astonishing level of ideological blindness. Mass migration and low or zero aviation emissions are not compatible for a generation or more. New technology will lower emissions but not elimiate them prior to 2050. Sometimes governing involves trade offs and this is one of them. People like to see their families in person and that for many (myself included) involves long haul flights. Its bonkers to issue visas to someone who lives a 10 or 12 hour flight from the UK and then tell them they shouldn't fly or in the case of my family for another country to do the same. Train and sea travel is only viable for our near neighbours and a large proportion of our current and historic migration is to and from countries outside of Europe.