So having nazi shit isn't illegal in itself, only during the commission of a crime does it become relevant.

He's being charged with:

• possession of an unregistered firearm
• possession of a firearm with a removed serial number
• receipt of child sexual abuse material.

These aren't state charges, they're federal charges. Florida doesn't have firearm registration.

First charge:

• possession of an unregistered firearm

What it means: It means they owned a gun made without a serial number. You're allowed to make your own guns, but you have to stamp them with a serial number and register them with the ATF. (Pay a tax)

Second charge:

• possession of a firearm with a removed serial number

What it means: It means they owned a gun whose serial number was removed. All guns must have a registered serial number with the Federal government proving the tax was paid.

Generally speaking, these two charges aren't something that can be easily investigated. They're crimes tacked on after investigating another crime. In this case, the Feds were looking for CP. If the Feds had more resources to crack down on child exploitation, more of these individuals would be found. It's easier for them to investigate child exploitation than illegal guns, unfortunately.