At 10-15% conversion efficiency, you're burning 85-90% of your energy just making the damn fuel, requiring 6-7× more renewable infrastructure than direct electrification. Current production costs are $15-25/gallon (not the fairy tale $2-3/gallon of jet fuel), and the physics won't magically improve to hit their "3× oil prices by 2050" fantasy. To replace global aviation fuel would demand a staggering 32,000 TWh of new clean energy generation – that's roughly equivalent to building 900 nuclear plants just to make luxury jet fuel while the rest of the grid still burns coal.
You've not actually addressed the cost points he makes. You seem to bediscounting the sheer cost effectiveness of renewable power because if an ideological opposition to it.
The wonderful thing about looking at how much something actually costs is you don't need to do all the work yourself - just look at the expense of the inputs and calculate your output. Solar panel electricity is absurdly cheap.
In any case it's obvious that current direct electrification is not feasible using current battery tech, so alternatives need to be explored. Unless we find a battery tech with 10x energy density batteries aren't likely to be viable in the air.