Eugene Parker and Ludwig Boltzmann are familiar with your argument, and I doubt you even have Lord Kelvin's credentials.

As Prof. Parker said, "We'll see who falls flat." (That's a paraphrase from memory; I doubt it's an exact quote.)

Boltzmann had a whole lot of math backing up his assertions. Among the many issues with what you posited, I highly doubt you have bothered to actually check to see if the force necessary to keep electrons from colliding with the nucleus would also be commensurate with what’s needed to counteract gravity at cosmological scales. Your theory is analogous to saying that we don’t need to invoke gravity to explain why the earth doesn’t spiral into the sun, because it could just be explained with solar photon pressure.

Sorry to have confused you, but the force that keeps atoms from imploding is (IIUC) of a different nature than that which keeps the universe expanding. They are both "dark energy", but I do not think they are the same "force".

I apologize for not making that clear, but I only know of their very basic nature, not their mathematical-physics relationships and differences. That's not my area of expertise. I'm a general systems person, so I have some very basic knowledge of how such systems behave. This is due to my curiosity about the universe and my own self, which has given me access to persons much more deeply connected than myself.

Note that Eugene Parker, too, had a lot of maths to back his claims up, but that didn't help him convince his peers. Only when we sent a probe up that could measure the solar wind did his detractors begin to stand down. That is always the way new levels of understanding are treated by the status quo.