If the neutron is a proton with an electron stuck to it, we have no need for a strong force to keep the atomic nucleus from falling apart. The natural affinity between protons and electrons is all that’s required to keep things together.
This isn’t a new insight. The original models of the atomic nucleus didn’t invoke the neutron. Instead, it had atomic nuclei made up of protons with electrons as glue.
This model is called the proton-electron atom.
Using this model, the assembly of large atomic nuclei from smaller ones is a straight forward matter of clicking protons into stable configurations with electrons tucked in between them.
This fits well with the particle model laid out in this book. There’s no need to invent anything different.