Emm… I know that particles are “spinners of light”, but I don’t see what the rest of what you said relates to the issue.
The train viewer is not aware of any helical paths going on. Regardless of how fast his relative frame might be moving to something else, all he sees is something spinning. That something can be spinning at the speed of light as he would measure light, it doesn’t really matter.
Someone down the tracks merely sees a spinner coming at him along its axis. The rotation of the spinner is transverse to the travel toward him, so the y and z components of the Lorentz remain zero. The only motion that is subject to Lorentz contractions is the x axis motion. Thus the spinner coming toward him looks just like his own spinner. Both of those frames could be zipping off through space and merely closing on each other. That wouldn’t change anything they perceived.
Adding energy and momentum to a different axis (the train’s motion) cannot alter the first axis’ momentum (the rotation), else conservation of momentum could not exist. Whatever is happening in one plane cannot have effect on any transverse axis. In effect, that would constitute “spooky action at a distance”.
The light spinner is the easy thing to visualize. No one can view a light spinner as doing anything but spinning at the same speed of light. If the spinner was mounted inline rather than transverse, the shape of the spinner would be affected and thus the distances would come into play, but that isn’t the case for the transverse spinner. There are no contractions or dilations of any kind.
The only reason any issue comes up is the fact that the train thinks it has traveled down the track faster than the station thinks it has. They could both see the spinners in parallel motion and spinning identically, especially if they were light spinners because every light spinner of the same size must be seen as spinning at the same speed. That is the fundamental concern of SR, the consistency of the measure of the speed of light.
There really isn’t any 2 ways about it. The train’s dilated time causes the train to count fewer spins. End of story.
That is all totally irrelevant as far as I can tell. YOU know that the light is traveling in a helical arc, or else you are yourself instead. The viewers have no perception of such an arc at all, but they MUST see the light spinner spinning at the speed of light. And in fact, perhaps the train’s spinner isn’t the one moving at all, but rather it is the station. The very fundamental issue of Relativity is that it doesn’t matter who is moving, they must observe the same speed of light and they cannot even know if they are traveling or not.