Doubt regarding choked flow equation

Main aim of keeping low pressure is to reduce drag while moving.Hence low pressure is maintained inside the tube.But the capsule is levitated using air bearings according to Elon musk concept.But the air bearings are pressurized.

What I am not getting is if there will be difference in pressure in 2 areas of tube wont the air move from high pressure to flow pressure.Also they are using choked flow equation for gap between tube and capsule.So acc to A1V1=A2V2, the pressure would be decreased in restriction and so the air should flow from front part to restricted area but we are already using air bearings at high pressure in restricted part. Doesnt these 2 situations contradict themselves??

In short we are using choked flow equation to determine mass flow due to decrease in pressure in space between tube and capsule.But at the same time we are using high pressure in same area for air bearings.How is that possible simultaneously?