Time dilation speculation

So she and her video recorder spent 18 hours on other side of the wormhole and something like only 1s or 2s passed for the others on Earth as the IPV dropped straight through from their perspective.

BUT!! Time dilation only happens if she would have been traveling at the speed of light and that too in reverse. Meaning if she were traveling at speed of light then time would run slower for her relative to the observers on Earth.

This means, 1s of her time would've been a high multiple like maybe 2 hours on Earth so 18 hours for her should've been 18*60*60*2 = 129,600 hrs = 14.8 years for people on Earth having elapsed.

Meaning she should've aged 18 hours while Earth people aged 14.8 years.

This didn't happen. In fact it was the reverse - she aged 18 hours while Earth people only aged 1-2s.

Why?

I believe the only answer here is the wormhole other end was indeed spinning at speed of light. I think this is the only way time travel can work - from the moment you have a wormhole endpoint that can be accelerated to light speed.

So Earth end is fixed and Vega end is spun at speed of light. When she is traveling time is elapsing normally for Earth and her. When she emerges from the wormhole time is slowing down for her and to Earth people, if they could see her, she'd be frozen in time.

She does her thing and this is the important part - she goes back through the same wormhole back to Earth - which is basically time travel into the past for her. And she emerges at the moment she left.

The movie doesn't explain many things and it is an amazingly made movie but leaves us with such interesting speculations.