What is the penalty for exceeding said limit in your fantasy?
edit
Just out of curiosity I took what seems to be the "average" of the reported number of billionaires in America as 800, and the average yearly CO2 from flying via the linked article at a high point of also say 800 tons (which is likely high but easy math). That works out to 640000 tons of CO2 from all the billionaires flying around in a year.
Another quick search on how much CO2 is produced in the USA per year came out as 5.2 billion metric tons.
That means these flights are accounting for 0.0123076923% of the USA's CO2 production ... or put another way it's a rounding error.