The contractor should be in as much hot water as this "floor" guy.
If my home, I would NOT allow the person back into my home. I would take pictures, document, and collect all evidence of the shoddy work. Then I would sit down and have a severe talk with the contractor and get some fast remedy on this job and get it fixed right. He is the boss of the sub and he might not have done his/her job.
The finish could have been reaplied within two hours only if it was water based polyurethane. OIL will take a good day or more depending on humidity.
Sanding or steel wooling is a must between each coat of sealant. Sanding was done by a drum sander I would suspect and he/she sat in one spot too long and not an even gently sweep. Sealing, sanding, and finish coat should all be applied in the direction of the grain of wood. swirls occure when the sand paper was taken perpendicular to the grains.
you migh need to take legal actions against the contractor on this.
But, do not let the original floor person back to do any work.