All science is materialistic

[Jehanne]

Whether photons are matter or not sounds like the question whether Pluto is a planet or not.  Photons curve space and they can cause a solar sail to accelerate through recoil, which is material enough for government work. Physics is about cataloguing what is.  Photons are.  They are physical, just as Higgs particles and gluons are. But there is an expectation they are essentially different from matter because when a positron and electron annihilate each other all you have left is photons. Then again, we know in high energy collisions this works the other way around, and photons can be intermediate states between colliding protons and any number of other particles, maybe like this:

Which, again, is to my point. The label (material, physical, etc) is irrelevant. What is important is whether the ideas are testable via observation.

You're pounding on open doors. Non-material explanations are not testable. Of the 20 million or so scientific papers published in the last century, cite a single one that addresses "non-material" forces.